Which of the following are true? 1. If velocity is constant and positive, then distance traveled during a time interval is the velocity multiplied by the length of the interval. 2. If velocity is positive but decreasing, using the velocity at the beginning of each subinterval in a rectangle sum gives an overestimate of the distance traveled. Select one: O a. Both 1 and 2 O b. Just 1 O c. Neither 1 or 2 O d. Just 2