Explanation:
a) Hammer hits a nail
Action: Hammer hitting the nail
Reaction: Nail Hitting the hammer.
B) . Earth's gravity pulls down on a book.
Action: Earth pull downward on the book.
Reaction: The Book pull's the Earth Upward.
C) A helicopter blade pushes air downward.
Action: Blade push air downward
Reaction: The force in pushes the helicopter upward.
