What condition is indicated by a person being lethargic?

Lethargy is a state characterized by a lack of energy and enthusiasm, which can often be indicative of an underlying health issue. When a person is described as lethargic, it typically suggests that they may not be feeling well, which aligns with the description of being "very sick and septic." Septic conditions, often involving severe infections leading to systemic inflammation, can cause significant lethargy due to the body's response to fight off the infection.

In contrast, the other options present states that imply normal energy levels or good health, which do not correspond with lethargy. A person who is energetic and alert, healthy and active, or rested and refreshed would not exhibit lethargy, as these descriptions suggest vigor and vitality. Thus, lethargy is more accurately associated with serious health concerns such as being very sick rather than a state of well-being.