Explanation
Auto-response rules are used to automatically send email responses to lead or case submissions based on the criteria you define. You can create one auto-response rule per object (lead or case) and configure multiple rule entries with different criteria and actions within that rule. To meet the requirement of sending different email notifications based on case priority, you need to create one auto-response rule for cases and configure three rule entries with filters for low-priority, medium-priority, and high-priority cases respectively. Then you need to select the appropriate email template for each rule entry action. References:
https://help.salesforce.com/s/articleView?id=sf.customize_leadsautor.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.customize_casesautor.htm&type=5

Explanation
A lookup field is a type of field that allows administrators to create a relationship between two objects by linking records from one object to another object. For example, a lookup field can link an account record to a purchase record by storing the account ID on the purchase record. A lookup field allows users to select an existing record from a pop-up window or create a new record from the same window. References:
https://help.salesforce.com/s/articleView?id=sf.relationships_lookup.htm&type=5

Explanation
Lightning app pages, Chatter, and dashboards are three items that are available in the mobile navigation menu.
The mobile navigation menu allows users to access different items in the Salesforce mobile app, such as objects, apps, or utilities. Users can customize their mobile navigation menu by adding or removing items and changing their order. References: https://help.salesforce.com/s/articleView?id=sf.app_nav_setup.htm&type=5

Explanation
To display only the proper lead sources based on the product category chosen, an administrator should create a dependency between the Product Category field and Lead Source field on Lead object. A dependency is a relationship between two picklist fields that restricts the values available in one picklist based on the value selected in another picklist. For example, an administrator can create a dependency that shows only Online Store and Social Media as lead sources if Product Category is Shoes, but shows only Trade Show and Magazine as lead sources if Product Category is Apparel. Creating a page layout for each category, creating business processes and record types for each category, or creating a single business process with record types for each category will not display only the proper lead sources based on the product category chosen.
References: https://help.salesforce.com/s/articleView?id=sf.customize_dependent.htm&type=5

Explanation
When users log in to Salesforce via the user interface, the system checks for authentication based on their profile settings and permissions. One of the settings is login hours, which specify the time range when users can log in to Salesforce based on their profile. Another setting is Two-Factor Authentication for User Interface Logins permission, which requires users to enter a verification code along with their username and password when they log in to Salesforce via the user interface. References:
https://help.salesforce.com/s/articleView?id=sf.users_profiles_loginhours.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.security_2fa_perm_ui_logins.htm&type=5