To determine the force that the volleyball exerts on Ana, we need to apply Newton's Third Law of Motion. Newton's Third Law states that for every action, there is an equal and opposite reaction. In other words, if one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
Given:
- Ana exerts a force of 20 N on the volleyball.
According to Newton's Third Law, the volleyball will exert a force that is equal in magnitude but opposite in direction to the force that Ana exerts on it.
Thus, the force that the volleyball exerts on Ana is:
[tex]\[
\text{Force exerted by volleyball on Ana} = 20 \, \text{N}
\][/tex]
Therefore, the correct answer is:
[tex]\[
\boxed{20 \, \text{N}}
\][/tex]
