Final answer:
Vasodilatation is a physiological response that occurs in reaction to elevated body temperature, as it aids in radiation and evaporative heat loss to cool the body.
Step-by-step explanation:
Vasodilatation in Response to Body Temperature
Vasodilatation is a physiological response where blood vessels widen or dilate. This process occurs for various reasons, one of which is to help the body regulate its temperature. Vasodilatation is a response to elevated body temperature. When the body’s temperature rises, vasodilatation allows for radiation and evaporative heat loss, helping to cool the body down. This response is especially important during activities such as skiing or running, as it prevents the body from overheating by increasing blood flow to the body's surface, where heat can be more easily dissipated into the environment. Contrarily, vasoconstriction occurs to conserve heat, bringing blood closer to the core and vital organs when the external temperature decreases. So, in response to the student's question, vasodilatation occurs because of option (c) elevated body temperature. Increased sympathetic activity typically leads to vasoconstriction, not vasodilatation, except for specific cases like skeletal muscles during the fight-or-flight response where it can lead to dilatation to increase blood flow.