You are conducting an experiment inside an elevator that can move in a vertical shaft. A load is hung vertically from the ceiling on a string, and is stationary with respect to you. The tension in the string is measured to be exactly equal to the force due to gravity on the load. No other forces are acting on the load. Which of the following statements about the elevator are correct?
A. The elevator is an inertial frame of reference.
B. The elevator is not an inertial frame of reference.
C. The elevator may be at rest for the duration of the entire experiment.
D. The elevator may be moving at a constant velocity upward.
E. The elevator may be moving at a constant velocity downward.
F. The elevator must be accelerating