The volume of a cylinder is given by the formula V = πr²h, where r is the radius and h is the height. In this case, r = 5 feet and h = 10 feet. Plugging in the values, we get V = π(5²)(10) = π(25)(10) = 250π cubic feet. Since 1 cubic foot is equal to 7.48 gallons, we can convert the volume to gallons: 250π cubic feet x 7.48 gallons/cubic foot ≈ 392.7 gallons. Answer: c) 393 gallons (rounded to the nearest whole number).