Select the most appropriate option to fill in the blank.

My grandfather will come here ___ a week.

Correct option is B

• The sentence requires a preposition indicating the time frame for the grandfather’s arrival.
• Within is appropriate, meaning “My grandfather will come here within a week”, implying any time up to a week from now.
• Before suggests prior to a specific point, not a duration. At is used for precise times, and with is irrelevant.
• Within a week is a common phrase for an event expected soon, fitting the context.
• The sentence reads naturally and grammatically correctly with within.
• Thus, within is the correct answer.