The correct answer
is A. Strength.Vigour is a feeling of great energy and enthusiasm. It can also refer to physical strength or force.
Strength is the quality of being strong. It can refer to physical strength, mental strength, or moral strength.
Boldness is the quality of being brave or daring. It can also refer to the quality of being confident or assertive.
Warmth is the quality of being warm or hot. It can also refer to the quality of being friendly or affectionate.
Enthusiasm is the quality of being excited or eager about something. It can also refer to the quality of being passionate or zealous.
In the context of the question, vigour is the most appropriate word to describe the feeling of great energy and enthusiasm.