In a baseball game the batter hits the ball into center field and takes off for first base. The catcher can only stand and watch. Assume that the batter runs at a constant velocity. Who measures the proper time it takes for the runner to reach first base, and who measures the proper length between home plate and first base?
(a) The catcher measures the proper time, and the runner measures the proper length.
(b) The runner measures the proper time, and the catcher measures the proper length.
(c) The catcher measures both the proper time and the proper length.
(d) The runner measures both the proper time and the proper length.