Select the correct option:
Not until the auditors had submitted their exhaustive report ____ the full extent of procedural lapses become evident.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1, i.e. did.
“Not until” at the beginning makes the sentence negative and requires inversion. In such cases, we use an auxiliary verb before the subject. The main verb here is “become” (base form), so it needs the auxiliary “did” to form the correct past tense structure: “did … become.”
Option Analysis:
did – correct because it forms the required inversion and matches “become”
had – would require the past participle “become,” and the structure would be incorrect here
was – does not fit with the base verb “become” and breaks the inversion pattern
has – present tense, does not match past context