Final answer:
The force primarily responsible for the airplane's climb is Lift (C), which is generated by the wings of the airplane as air flows over them.
Step-by-step explanation:
The force primarily responsible for the airplane's climb is Lift (C).
Lift is the force that opposes gravity and allows the airplane to rise into the air. It is generated by the wings of the airplane as air flows over them. The shape of the wing and the angle of attack (the angle between the wing and the oncoming air) contribute to the creation of lift.
Thrust (A) is the force provided by the engines that propels the airplane forward. Drag (B) is the resistance force that acts opposite to the direction of motion and opposes the airplane's movement. Gravity (D) is the force that pulls the airplane downwards towards the Earth.