B.

External ID

C.

Review which status choices are needed for each record type and create support
processes for each that is necessary.

Support processes allow you to define different status values for different record types on cases.
References: https://help.salesforce.com/s/articleView?id=sf.customize_support_process.htm&type=5

D.

Validation Rules

To require users to follow the status values as they are on the path and
prevent them from reverting back to previous status values, the administrator should use validation rules that check if the statusfield value is changed from one value to another value that is not allowed by business logic. For example, if status values are New > In Progress > Closed, then a validation rule can check if status is changed from Closed to In Progress or New, and show an error message if true. Predefined Field Values, Global Value Picklists, and Dependent Picklists are not able to enforce status progression or prevent status
reversion.
References:https://help.salesforce.com/s/articleView?id=sf.validation_rules_over
view.htm&type=5

A.

The pending Chatter post will be canceled.

A pending Chatter post is a post that has been scheduled to be published at
a future date and time. However, if the user who created the pending Chatter  post isdeactivated before the scheduled date and time, then the pending Chatter post  will becanceled and will not be published. This is because deactivated users cannot create or edit posts in Chatter.
References:https://help.salesforce.com/s/articleView?id=sf.collab_scheduled_posts.htm&type=5https://
help.salesforce.com/s/articleView?id=sf.collab_deactivated_users.htm&type=5

B.

Download into a Trailhead Playground.

C.

Install in a sandbox.

A Trailhead Playground is a free, online learning environment that allows you
to try out Salesforce features and apps. You can use a Trailhead Playground to test out an app from the AppExchange before you install it in your production org. A sandbox is a copy of your production org that you can use to test changes and new features. You can install an app from the AppExchange in a sandbox to see how it works in your environment. Testing anapp in a production org is not recommended, as it could affect your live data. Checking edition compatibility is important, but it is not a way to try out an app.

C.

Component Visibility

Component visibility allows you to restrict the visibility of a related list based
on a permission set.
References:https://help.salesforce.com/s/articleView?id=sf.dynamic_forms_component_visibility.htm&type=5

C.

Utility Bar.

Utility bar is a feature that is available in a Lightning app where visibility is
limited to the Salesforce mobile app. Utility bar allows users to access common productivity tools, such as notes, history, recent items, and more, from any page in the app.
References:https://help.salesforce.com/s/articleView?id=sf.app_builder_utility_bar.htm
&type=5

C.

Flow builder

Flow builder is an automation tool that allows administrators to create flows
that guide users through screens, collect data, and perform actions on records. It can be used to simplify the account creation process by creating a screen flow that shows only the essential fields for creating an account and hides any unnecessary fields or sections from the page layout. Approval process, workflow rule, and validation rule are not automation tools that can simplify the account creation process; they are used fordifferent purposes such as approving records, updating fields, or enforcing data
quality.
References:https://help.salesforce.com/s/articleView?id=sf.flow_builder.htm&type=5