A book is resting on a table. There is a normal force from the table on the book. According to Newton’s third law, there must be a reaction to this force. What is the reaction?
A. The weight of the table, acting downwards.
B. A contact force on the book, acting downwards.
C. The weight of the book, acting downwards.
D. A contact force on the table, acting downwards.
(Explain why the answer is D)