D.They are equal in magnitude and opposite in direction
Explanation:
Newton's third law states that the action force is always associated with a reaction force.
When a body 'A' exerts a force on body 'B', it is called the force of action.
When the body 'B' in turn resist the force of 'A' is called the reaction force. It is the reactive force acted upon by the body 'B' on 'A'.
This reaction force is equal in magnitude of the action force.
If the two bodies remain in the same horizontal line, the 'A' exerts a force in the direction towards 'B' and the body 'B' exerts a reaction force in the direction towards 'A'.
Hence, the two forces that are exerted by the bodies are equal in magnitude and opposite in direction.
