**Concept: The question tests on the area of Combinatorics**

**Solution:**

The number of revolutions taken by a circular surface of radius r to travel a distance d is given by n = d / 2πr

Here d = 75 yards = 75 * 3 = 225 feet

r = 2.5 feet

Assuming π = 22/7

n = 225/2∗22/7∗2.5=14.31 ≈ 14

Time taken for 1 revolution = 30 seconds

Therefore time for 15 revs = 14 * (1/2) = 7 minutes**Option D**