Which of the following statements best explains why a book resting on a table is in equilibrium?
a. the acceleration due to gravity is 9.8 m/s 2 for both the book and the table.
b. there is a net force acting downward on the book.
c. the weight of the book equals the weight of the table.
d. the weight of the book and the table's upward force on the book are equal in magnitude but opposite in direction.