Bonjour,
a) Since the resistance of air is neglected, the only action exerted on the apple is its weight.
b) The apple is moving down with an accelerated rectilinear motion.
c) The correspoding chronophotograph is the c : The motion is rectilinear and the distance between two successive positions is increasing, which means that the speed is increasing during the motion, so that it's an accelerated motion.
