Let s(t) be a function giving the position of an object at time t. Which of the following statement is true? Select one: O a. The speed of the object at time t is given by |s' (t) |. O b. The velocity of the object at time t is given by v(t) = s'(t). O c. The acceleration of the object at t is given by a(t) - v'(t) = s"(t). O d. All of these are true. ge