Which word best represents energy and vitality?

The word "vigor" is the best choice to represent energy and vitality because it specifically refers to physical strength, good health, and mental energy. When someone is described as having vigor, it implies they possess an enthusiastic and dynamic quality that suggests they are full of life and capable of vigorous activity or effort. This term often conveys a sense of liveliness and robustness, which aligns perfectly with the concepts of energy and vitality.

The other options convey different meanings that do not align with the idea of energy and vitality. Fatigue refers to a state of tiredness or exhaustion, while indifference expresses a lack of interest or concern, and listlessness describes a state of lacking energy or enthusiasm. These terms reflect a deficiency of energy and vitality, making them unsuitable in this context.