The answer is C, First you must find the length of the diagonal gravel path and you can use Pythagorean Theorem to do this. 24^2+32^2=c^2 and solve for c which will get you 40 feet. Now, solve for the area of the path by multiplying 40*2 (2 feet wide) which will get you an area of 80 square feet. Multiply 80 by 3.5 and then the answer is $280. Hope this helped you :)