The answer is C. The scenario that represent the exponential growth is no other that a species of fly doubles its population every month during the summer. Doubling is exponential. The three that is included in the choice is linear which is a water tank is filled at a rate of 2 gallons/minute, a vine grows 6 inches every week and a car increases its distance from a garage as it travels at a constant speed of 25 miles per hour.