The app builder needs to do two steps to make the custom Lightning App available to the internal users at Universal Containers:
* Create a subdomain using My Domain: My Domain is a feature that allows an organization to set up a custom domain name for their Salesforce instance. This is required to use custom Lightning components
* and apps in Salesforce1.
* Build a Custom Tab for the app: A custom tab is a tab that displays any custom object or web page in Salesforce. This is required to make the custom Lightning App accessible from the navigation menu or app launcher2. Option A and B are not necessary steps to make the custom Lightning App available to the internal users.

The email button item will not be visible on the Lightning record page if the page layout includes the case feed component or if the email button contains JavaScript. The case feed component replaces the standard buttons on the page layout with actions in the feed. The email button item will not work if it contains JavaScript because JavaScript buttons are not supported in Lightning Experience.

To manually share individual records with specific people or group of people on a case by case basis, users can use public groups, roles, or users. Public groups are collections of users, roles, or other groups that can be used to share access to records. Roles define the level of access that users have to their organization's data based on their position in the hierarchy. Users are individual people who log in to Salesforce and have access to records based on their profile, role, and sharing settings.

The best practice that the app builder should follow when building out automation is one record change process per object. A record change process is a type of process in Process Builder that starts when a record is created or updated. Having one record change process per object can avoid conflicts or errors when multiple processes try to update the same record at the same time. Option A is incorrect because one workflow rule per object is not a best practice, as workflow rules are considered legacy tools and have limitations compared to Process Builder. Option B is incorrect because one flow per object is not a best practice, as flows are more complex and require more resources than processes. Option C is incorrect because one invocable process per object is not a best practice, as invocable processes are used to invoke other processes from within a process or a flow.

The best way to solve this problem is to filter components by device using Form Factor. Form Factor is an attribute that can be applied to components on a Lightning record page to control their visibility based on the device type, such as desktop, phone, or tablet. By using Form Factor, the app builder can hide some components that are not relevant for mobile users, such as charts or reports, and show only the components that are necessary for data entry, such as fields or actions. This way, the mobile users do not have to scroll through all the components and can enter data more easily. Reordering the fields may not solve the problem completely, as there may still be too many components on the page for mobile users. Updating the training documentation may not help either, as it does not address the root cause of the problem, which is the layout of the page. Deselecting the phone radio button on the Lightning record page assignment may not be desirable, as it will prevent mobile users from accessing the record page at all, which may affect their productivity and functionality.