Which of the following pairs of forces constitutes a single action–reaction pair under Newton’s third law?
a) The weight of a book resting on a table and the normal force exerted by the table on the book.
b) The tension at the two ends of a rope pulled steadily by two opposite forces.
c) The gravitational pull of Earth on the Moon and the gravitational pull of the Moon on Earth.
d) The weight of a hanging lamp and the tension in its supporting cord.