Explanation
A lookup field is a type of field that creates a relationship between two objects and allows users to select a record from one object as a value for another object. A lookup relationship creates a one-to-many relationship between two objects, where each parent record can have many child records but each child record can have only one parent record. A lookup relationship also allows limited access to child records, meaning that users can see only those child records that they have access to based on their profile permissions and sharing settings. References: https://help.salesforce.com/s/articleView?id=sf.relationships_lookup.htm&type=5

Explanation
Two functions that an administrator should use when creating a validation rule are:
Error condition formula, which defines when an error should occur based on record fields and values Error message location, which specifies where on the page layout an error message should appear when triggered by an error condition formula Formula return type and rule active date are not functions used for validation rules. References:
https://help.salesforce.com/s/articleView?id=sf.validation_rules_overview.htm&type=5

Explanation
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 is deactivated before the scheduled date and time, then the pending Chatter post will be canceled and will notbe 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