The correct answer is A. Endurance.
Endurance is the ability to sustain an activity or effort over a long period of time. It is often used in the context of physical activity, but it can also refer to mental or emotional endurance.
Intensity is the degree of strength or force with which something is done. It can be used to describe physical activity, but it can also refer to mental or emotional intensity.
Eagerness is a strong desire to do or experience something. It is often used in the context of positive emotions, such as excitement or anticipation.
Energy is the ability to do work or to move. It can be used to describe physical energy, but it can also refer to mental or emotional energy.
In the context of the question, stamina is the ability to sustain an activity or effort over a long period of time. This is most closely aligned with the definition of endurance. Intensity, eagerness, and
energy are all related to stamina, but they do not fully capture the meaning of the word.