Final answer:
The correct forces acting upon a trapeze artist are gravity and tension, with air resistance present as a less significant force.
Step-by-step explanation:
The forces acting upon a trapeze artist swinging are gravity and tension. Gravity is a pervasive force that always acts downward on the trapeze artist due to the Earth's gravitational pull. Tension is the force exerted by the trapeze cable, which supports the trapeze artist, acting upwards and typically having both horizontal and vertical components due to the nature of the swing. Additionally, there is air resistance, which acts against the motion of the trapeze artist through the air, although it is often much less significant than the forces of gravity and tension. The correct option in this situation is C) Tension and air resistance.