The solution that the app builder should use to meet DreamHouse Realty's needs is Master-Detail Child Object. A master-detail relationship can be used to create a parent-child relationship between two objects, where the child records inherit the sharing and security settings of their parent record. The app builder can create a roll-up summary field on the parent object to calculate the highest value of all child records. Option B is incorrect because Text Area (Long) is a field type that allows users to enter up to 131,072 characters on one line, which is not suitable for this requirement. Option C is incorrect because Multi-select Picklist is a field type that allows users to select multiple values from a predefined list, which is not suitable for this requirement. Option D is incorrect because Lookup Object is not a valid term, but rather Lookup Relationship, which is a type of relationship that links two objects together, but does not support roll-up summary fields.

Sales rep B has implicit access to the Account because of the manual sharing of the Opportunity. Implicit sharing grants access to parent records when a user has access to a child record. Sales rep B was not added to the Account team, sharing set is not applicable for private sharing model, and Account was not manually shared.

The app builder should use the Path feature to provide the functionality that the VP of Sales wants. The Path feature allows an app builder to create a visual representation of the stages in a business process, such as the Opportunity sales process. The app builder can also add key fields, guidance, and resources for each stage to help sales reps gather information and complete tasks4. Option A, C, and D are not features that can provide this functionality.

A: Changing the Lead Matching Rule to 'Block on create' will directly prevent duplicates at the point of lead creation based on defined criteria.
C: Changing the Lead Duplicate Rule to 'Bypass Sharing Rules' allows the system to compare leads across the entire organization regardless of the user's access level, which is crucial especially when OWD is set to 'Private'.
Reference:
Salesforce Help - Duplicate Management

A report type that is in a status of In Development is not available for users to select when creating a new report. The app builder needs to change the status to Deployed to make it visible to users