Answer: the first option is the correct answer.
Explanation:
Martin runs 3/4 mile three days a week. We would assume that he runs a total of 3/4 miles in three days of each week.
In four weeks the number of days that he runs would be
3 × 4 = 12 days
Since he runs 3/4 miles in 3 days, the number of miles that he would run in 12 days would be
3/4 × 12 = 9 miles
He would run 9 miles in four weeks