Final answer:
The force not mentioned in the passage is tension, which is a force transmitted through a string or rope when it is pulled tight and not relevant to a person leaning against a wall.
Step-by-step explanation:
The force not mentioned in the passage is tension. In physics, tension is the force transmitted through a rope, cable, or wire when it is pulled tight by forces acting from opposite ends. The forces discussed in the passage are the force of gravity pulling the person towards the Earth, the normal force exerted by the ground supporting the person, and the normal force exerted by the wall when the person leans against it. Tension typically acts along the length of a wire or rope and is not present in the scenario described where the person is leaning against a wall.