The expression "How many miles did Gretchen jog yesterday" states a fact that occured in the past, and asks about a specific number that is defined and cannot change.
Since the answer for this question is only one number (other values would be incorrect), the question shown is not statistical (B), because there is one known answer to this question (B).
Statistical questions don't have an absolute value (just one value) as an answer, but a range of values.
