Which full report correctly marks the earlier past event in the core-backshift contrast? Direct from the custodian: "I locked the archive before the alarm sounded."
The custodian said she had locked the archive before the alarm sounded.✓Correct answer
The custodian said she has locked the archive before the alarm sounded.
The custodian said she had lock the archive before the alarm sounded.
The custodian said she did had locked the archive before the alarm sounded.
Explanation
Had locked marks the archive action as earlier than the alarm, preserving the sequence highlighted by before. Has locked uses a present perfect in a past narrative, and the remaining forms combine auxiliaries with invalid verb forms.