Three attributes that are true regarding Subscriber Pages are:
* Subscriber Pages can include additional standard Salesforce B2B Commerce components such as featured products, category tree, and mini cart. These components can be added to the Subscriber Pages by using the CCRZ.pagevars.pageLabels and CCRZ.pagevars.pageSections objects, which contain the page labels and page sections that are defined in CCAdmin.
* Subscriber Pages allow customers to quickly create new custom pages for their storefront. These pages can be used to display any content or functionality that is not available in the default pages, such as FAQs, testimonials, or promotions.
* Out of the Box, Subscriber Pages are completely blank HTML pages. These pages do not have any predefined layout or content, so the user can customize them according to their requirements. The user can use Visualforce, HTML, CSS, JavaScript, or any other web technologies to create their own Subscriber Pages. Salesforce References: B2B Commerce and D2C Commerce Developer Guide, Subscriber Pages

Two Salesforce B2B Commerce Visualforce pages that must be enabled at a Salesforce Community level to make the out of the box SEO functionality available are:
CCSizeIndex: This page generates a sitemap.xml file, which is a file that lists all the pages and resources on a site that can be crawled by web crawlers. The page uses the configuration settings CO.SiteMapIncludeProducts and CO.SiteMapIncludeCategories to specify which products and categories should be included in the sitemap.
CCCatSiteMap: This page generates a category sitemap file, which is a file that lists all the categories on a site that can be crawled by web crawlers. The page uses the configuration setting CO.SiteMapCategoryDepth to specify how many levels of subcategories should be included in the category sitemap. Salesforce Reference: B2B Commerce and D2C Commerce Developer Guide, Sitemap Files

Explanation
Two components in a B2B store template that a developer can use to customize a storefront page are My Lists and Product List. My Lists is a standard component that displays and manages lists of products that customers can create, save, or share in the storefront. A developer can use this component to enable customers to organize their favorite or frequently purchased products into lists and access them easily. Product List is a standard component that displays and filters products from one or more product lists in the storefront. A developer can use this component to showcase products from different categories or collections and allow customers to browse or search for products based on various criteria. Order List is not a component in a B2B store template, but rather an object that stores information about orders placed by customers in the storefront.
Address List is not a component either, but rather an object that stores information about addresses associated with customers in the storefront. Salesforce References: [B2B Commerce Developer Guide: My Lists Component], [B2B Commerce Developer Guide: Product List Component], [B2B Commerce Developer Guide: Order List Object], [B2B Commerce Developer Guide: Address List Object]

Explanation
To implement a custom child checkout component for a B2B or B2C store created with an LWR template, the developer must implement the CheckoutStep interface from the commerce/checkout module. This interface defines the methods and properties that the child component must have to communicate with the parent checkout component and the checkout data provider. The CheckoutStep interface extends the UseCheckoutComponent interface, which provides the common functionality for all checkout components, such as loading and saving data, reporting validity, and handling errors.
The other options are not correct because:
* A. CheckoutSavable is not a valid interface for a custom child checkout component. There is no such interface in the commerce/checkout module or the Lightning web component framework.
* B. Checkoutoutinterface is not a valid interface for a custom child checkout component. There is no such interface in the commerce/checkout module or the Lightning web component framework.
* C. CustomCheckout is not a valid interface for a custom child checkout component. There is no such interface in the commerce/checkout module or the Lightning web component framework.
References:
* Create a Custom Checkout Component for a B2B or B2C Store (LWR)
* CheckoutStep Interface
* UseCheckoutComponent Interface

The Global JavaScript Object that should be extended when writing custom Remote Actions is CCRZ.cc. This object contains all the Remote Actions that are defined in the cloudcraze managed package, which can be overridden or extended by subscriber code. The object also provides a mechanism for registering custom Remote Actions that can be invoked by the user interface components. For example, CCRZ.cc.customAction = function(params, callback){ // do something } will define a custom Remote Action named customAction that can be called by CCRZ.cc.customAction(params, callback). Salesforce References: B2B Commerce and D2C Commerce Developer Guide, Remote Actions