Final answer:
A person is at the greatest risk of developing hypothermia when exposed to low body temperature conditions, which can lead to a dangerous decrease in core body temperature.
Step-by-step explanation:
Hypothermia is a condition characterized by a dangerous decrease in core body temperature, typically below 34.4 degrees C (94 degrees F). This condition poses the greatest risk when the body is subjected to prolonged cold temperatures and wherein the body's mechanisms for heat generation are overwhelmed or depleted. In such a scenario, a person's core body temperature can drop below the necessary threshold for normal metabolic function, leading to serious health risks including confusion, lethargy, and in severe cases, loss of consciousness and death. Therefore, the condition under which a person is at the greatest risk of developing hypothermia is C) Low body temperature.