If an object's position is described by d (t) = 1 - 12 + 1, where d is distance (meters) and t is time (seconds). Which of the following describe the behavior of d" (1)? o d" (t) is always positive. o d" (1) is positive when d(1) is concave up t > - andd"(t) is negative when d(1) is concave down for t o d" (1) is always negative