A man inside a sturdy box is fired out of a cannon. Which of the following statements regarding the man's sensation of weightlessness is correct?
a) The man senses weightlessness only when he and the box are traveling upward.
b) The man senses weightlessness only when he and the box are traveling downward.
c) The man senses weightlessness when he and the box are traveling both upward and downward.
d) The man does not sense weightlessness at any time of the flight.