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 answer is B.
When customer invitations are enabled for Chatter groups, invited customers get limited collaboration access. Salesforce documentation states that customers can see only the groups they're invited to and can interact only with members of those groups.
A is incorrect because invited customers do not automatically get broad group-invitation rights. C is incorrect because Chatter customer access does not grant access to Account records. D is incorrect because customers are invited to specific groups; they do not receive general public-group request access.

The correct answers are A. Streams and D. Out of Office.
Streams allow users to combine multiple Chatter feeds into one custom feed, making it easier to monitor updates from important people, records, and groups. This directly solves the issue of gathering feed updates from core team members. Salesforce documentation describes Chatter streams as custom feeds created by combining multiple related feeds into one feed.
Out of Office helps team members understand who is available to respond. Salesforce documentation explains that users can schedule and customize an out-of-office message and display it next to their name in Chatter.
Why the other options are incorrect:
Topics help categorize Chatter content but do not directly gather core-team feeds or show availability.
Polls are useful for collecting opinions, but they do not solve feed monitoring or availability visibility.

The correct answers are A. Create a master-detail relationship field on Application to Open_Position and B. Create a master-detail relationship field on Application to Job Candidate.
This requirement describes a many-to-many relationship: one Job Candidate can apply for multiple Open Positions, and one Open Position can have multiple Job Candidates. The correct Salesforce design is to use a junction object, which in this case is Application__c.
Salesforce documentation states that many-to-many relationships can be modeled using master-detail relationships between a junction object and the two related objects.
So Application__c should have:
A master-detail relationship to Job_Candidate__c
A master-detail relationship to Open_Position__c
This allows applications to appear on the Job Candidate record and also on the Open Position record.
C and D are incorrect because the relationship fields should be created on the junction object, Application__c, not from the parent objects back to Application.

The correct answers are C. Lightning App Builder and D. Lightning components in Setup.
In Lightning App Builder, custom Lightning components that are configured for use in Lightning App Builder appear in the Lightning Components pane.
In Setup → Lightning Components, Salesforce allows admins to view a list of Lightning Web Components and Aura components in the org.
Why others are incorrect:
A . Visualforce components in Setup lists Visualforce custom components, not Lightning components.
B . Salesforce Optimizer App analyzes org configuration and recommendations; it is not the place to list available custom Lightning components.