Final answer:
According to Newton's Third Law of Motion, if a book exerts a downward force of 5N on a table, the table will push back up with an equal force of 5N.
Step-by-step explanation:
The student's question pertains to the force exerted by a book on a table and the force the table exerts in response. This is an example of Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. Therefore, if a book pushes down on a table with a force of 5N, the table pushes back up with a force of 5N as well. The correct answer to the student's question is A) pushes back with a force of 5N.