ok, got into an argument with a kid in my physics class about this one... Which of the following are third-law partners? a. A thrust force from its propeller pulls a plane forward; a drag force pushes it backward. b. A car exerts a forward force on a trailer; the trailer tugs backward on the car. c. A motorboat propeller pushes backward on the water; the water pushes forward on the propeller. d. Gravity pulls down on a person sitting in a chair; the chair pushes back up on the person. I just said d would be...he was saying b,c,and d...but i'm thinking there is a third force acting on both number b and c which will not make them equal and opposite in magnitudes.