Final answer:
Option (B), The total metabolic rate increases when exposed to cold temperatures as the body works harder to generate heat to maintain its internal temperature.
Step-by-step explanation:
When an individual is exposed to cold temperatures, the total metabolic rate increases. This rise in metabolic rate occurs because the body needs to generate additional heat to maintain its internal temperature. External temperature influences the basal metabolic rate (BMR). Exposure to cold temperatures causes an increase in the BMR to produce the extra heat needed to maintain the body's internal temperature. However, mechanisms like hibernation, which some organisms utilize, can achieve energy conservation during cold periods without increasing the metabolic rate.
Additionally, as cold temperatures can cause ATP to degrade, more energy in the form of ATP must be synthesized through cellular respiration to maintain body heat. It's also worth mentioning that while larger animals have higher BMRs per body weight due to their greater surface area, smaller animals must expend more energy to maintain their size, adding to the complexity of how different organisms manage their metabolic rate in response to cold.