Answer:
D) the force of gravity from the rock on the Earth
Step-by-step explanation:
When a rock is under free fall , it is acted upon gravitational force by the earth . This is action force by the earth on the rock . According to newton's third law , there will be a reaction force also . Force is creating due to mutual attraction between earth and rock so rock will also exert gravitational force on the earth . Hence, that force will be reaction force .
Force due to rock on the earth will be reaction force , according to newton's third law.