LEFT(Account.Zip_Code_c, 5) is the correct formula to display only the first five digits of Zip Code from the parent Account. LEFT function returns the specified number of characters from the left side of a text string. Account.Zip_Code_c is the custom text field that stores the Zip Code on Account object. 5 is the number of characters to return from the left side of the Zip Code. The other options are not valid formulas or functions.

Apex. This is correct because Apex is a programming language that can perform complex logic and manipulate data in Salesforce. Apex can be used to create a trigger on the opportunity object that copies the value of the billing state from the related account record when the opportunity is created, and prevents it from being changed afterwards. The other options are not suitable for this requirement because they either cannot copy data from a related object (formula field, roll-up summary field) or cannot prevent data from being changed (workflow).

The primary object selection is locked once the custom report type has been saved. This means that the app builder cannot change the primary object later. The other options are not true.