The app builder should use Apex code to update a field on the parent record when a child record connected via lookup is deleted. Apex code is a programming language that allows developers to execute complex logic on the Salesforce platform. Apex code can be triggered by certain events, such as insert, update, delete, or undelete of records. In this case, the app builder can write an Apex trigger that runs after a child record is deleted and updates a field on the parent record accordingly. Option A, B, and D are not automation tools that can perform this task.

The best field type to use for the Planet Details field is Rich Text Area. This field type allows users to enter formatted text, images, and links. Long Text Area does not support images and links, Multi-Select Picklist does not allow text entry, and URL only allows a single web address.

Launch a new approval process that has automatic submission enabled as an initial submission action, and Create a new approval process that has automatic submission enabled in the entry criteria. These are correct because both options allow the deals to be automatically submitted for approval without requiring any action from the sales rep. The automatic submission can be configured either as an initial submission action or as part of the entry criteria

Criteria-based sharing rules are the best tool to use for automatically sharing records based on specific criteria, such as the opportunity type being "Service Agreement." This rule can share opportunities with all users in a particular role, such as the Service Manager role, when the criteria are met, thereby adhering to the private sharing model while still providing necessary access.
A: Owner-based sharing rules focus on the record owner's role or group, not the record type.
C: Apex sharing is used for more complex scenarios not easily handled by declarative sharing settings.
D: Manual sharing is not scalable or automatic.
Reference: Using Criteria-Based Sharing Rules on Salesforce Help

The import wizard only allows values to be imported into a dependent picklist if they match the appropriate controlling field. This ensures data integrity and prevents invalid values from being imported. Custom picklist fields can be either controlling or dependent fields. This allows the app builder to create custom dependencies between custom picklists. Checkbox fields can be controlling fields but not dependent fields. This allows the app builder to create dependencies based on checkbox values, such as true or false. Multi-select picklist fields can be dependent picklist fields but not controlling fields. This allows the app builder to create dependencies based on multiple values selected in a multi-select picklist field. Standard and custom picklist fields can be dependent fields, but not all standard picklist fields can be controlling fields. Some standard picklist fields, such as Lead Status or Opportunity Stage, cannot be controlling fields because they are used in other processes, such as lead conversion or sales path