4. why do opportunity costs increase as you make more and more
butter and fewer guns?

answer:

a possibility is  vasodilation.

"sweat  secretion stops when body temperature returns to normal. blood vessels supplying blood to the skin can swell or dilate - called  vasodilation."

"to maintain homeostasis, the blood vessels in your skin dilate to allow more blood flow to the surface of your body where it disperses the heat. you won’t feel the vasodilation, but you certainly will feel yourself sweating."

explanation: