The correct answer is C. Two Master-detail relationships on a new custom object.
This is a many-to-many relationship: one Contact can be related to many Solar Projects, and one Solar Project can be related to many Contacts. Salesforce's standard declarative design for many-to-many relationships is a junction object. A junction object is a custom object with two master-detail relationships connecting the two related objects.
A is incorrect because the two master-detail relationships belong on the new junction object, not directly on Contact and Solar Project.
B can technically relate records, but it is not the standard Salesforce many-to-many model tested here.
D does not correctly create a scalable many-to-many model.

The correct action is to validate the inbound change set in Production before the deployment window.
Salesforce states that an inbound change set can be validated without deploying changes, and validation shows the same success or failure messages that would occur during an actual deployment.
This helps the app builder confirm whether Apex tests, dependencies, and deployment requirements will pass while the developer is away.
Why not others:
A is wrong because removing Apex classes would remove required code.
B is wrong because deployment validation is done from the inbound change set in the target org.
C is not the standard change-set validation process.

The correct answers are A. Lightning App Builder and D. Quick Action.
A Lightning component can be exposed for use in Salesforce pages through supported targets such as App Page, Home Page, and Record Page, which are configured through Lightning App Builder. Salesforce developer documentation also confirms that components can be configured as quick actions using targets such as lightning__RecordAction or lightning__GlobalAction .
C). Validation Rule is incorrect because validation rules are business logic formulas, not places where Lightning components are placed or rendered. B. Time Failure is not a valid Salesforce area for using Lightning components based on the given option wording.

The correct answer is C.
The app builder needs to display only the first five digits from the parent Account's ZIP+4 custom text field.
Salesforce's LEFT() function returns a specified number of characters from the beginning of a text string, so the correct formula is:
LEFT(Account.Zip_Code__c, 5)
Salesforce formula documentation confirms that LEFT returns characters from the beginning of a text string.
BEGINS() checks whether text starts with specific characters. LPAD() pads text to a specified length. TEXT() converts certain data types to text, but it does not extract the first five characters.

The best option is a managed package from AppExchange.
Managed packages are designed for distributed apps where the provider can deliver upgrades. Salesforce documentation states that upgrades are supported for managed packages only. This reduces manual maintenance compared with unmanaged packages or custom open-source development, where updates typically require more manual replacement, deployment, or rework.
Why not the others? Unmanaged packages and open-source custom development can be useful, but they do not provide the same upgrade path and vendor-managed maintenance model as a managed AppExchange package.