Extent questions are typically understood as questions that explore the magnitude or scope of a problem. They help in understanding how large or significant the issue is. Given the options presented, the most accurate choice would be:
Questions that explore the magnitude of the problem.
However, if the option "Both A and C" implies that it encompasses both extent and timing questions, it would not be accurate to categorize extent questions as defining timing. Therefore, the best answer is just focused on the magnitude aspect.
If "Both A and C" refers to more broadly encompassing different aspects and not just limitations of the extent, it could potentially be a misleading or less accurate choice. Hence it's important to consider the context.