I am sure I would have regretted it if I ________ to take the job.  would agree  would have agreed  did agree  had agreed

This sentence is a conditional statement reflecting on a past action that did not happen. The correct option needs to indicate a past perfect condition.

Analysis

1. Understanding the sentence structure: The phrase "I would have regretted it if I ________ to take the job" requires a perfect conditional form in the blank.

2. Evaluating options:

   • would agree: This is incorrect as it is in simple present and does not fit the past conditional.
   • would have agreed: This is a valid conditional form and suggests that the agreement did not happen.
   • did agree: This is incorrect because it indicates a past action that was in fact completed, rather than a conditional reflection.
   • had agreed: Similar to "would have agreed," this form is correct and indicates that the action did not happen.

Correct Answer

The correct choice is "had agreed".

So, the complete sentence would read: "I am sure I would have regretted it if I had agreed to take the job."