Question

blood vessels constrict when the body is cold, a process known as what?
vasodilation
increase of diameter
vasoconstriction
vasodilation followed by vasoconstriction

Explanation:

Vasoconstriction is the narrowing of blood vessels. When the body is cold, blood vessels constrict to reduce heat loss. Vasodilation is the opposite (widening of blood vessels). "Increase of diameter" is also related to vasodilation. The described process is simply vasoconstriction, not a sequence of vasodilation - vasoconstriction.

Answer:

C. Vasoconstriction