Halp i have too more questions but it's in another pls halp

Which of the following would be a body response when stepping outside without a coat on a snowy day? a. senaceous glands. secrete more senum b. more liquid is transported by the body to the skin fir insulation c. blood vessels in the skin narrow and contract d. blood vessels in the skin expand

What causes darkening of the skin as melanin production increases

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?