2 t O X A pump allows water to flow into a pool at the rate of r (t) = 2t liters per minute, where t is the time in minutes since the pump was turned on. Which of the following defines a function that measures the accumulation of water in the pool during the time period from t = 1 to t = x as the variable a moves along the t-axis as shown in the figure above? A f (20) = 220 B f (2) = 1+2x c f (x) = 2tdt D f () = 2tdt