Answer: 3) the point between 2 objects where they balance each other
Explanation:
The center of mass of two bodies about which the bodies orbit and balance each other is known as Barycenter. It is the point of balance of two or more celestial bodies. The Barycenter determines the orbit of the celestial bodies.
For example: the binary stars orbit a common center of mass. Pluto and its moon Charon revolve about their Barycenter.
Hence, the correct option is 3.