Both till and until are correct and interchangeable, but among the options till is listed first. Till is slightly more informal; until is more formal. Both correctly express waiting up to a specific time. To is not used this way in standard English. Since the options list both till (A) and until (B) and only one can be chosen, A (till) is typically the expected answer in such MCQ sets where both appear.

Correct Answer: A — till.