Context: Isaac Newton was born in the 1600s and studied how objects move. He discovered three fundamental laws about forces and motion. According to Newton's third law, for every force, there is an equal and opposite force.
Consider the following force:
Quincy is pushing on his friend's wheelchair.
According to Newton's third law, what other force must be happening?
A. The wheelchair is pushing on Quincy.
B. The wheelchair is pulling on Quincy.
Determine the correct option from the provided choices and reply with its corresponding letter.

A