You will be successful in the interview ____ you have confidence. A. before B. once C. until D. thou

You will be successful in the interview ____ you have confidence. A. before B. once C. until D. though

The correct answer is B. once.

The sentence would be:
"You will be successful in the interview once you have confidence."

This implies that success will come when you gain confidence, emphasizing the condition necessary for success.