How do people acclimatized to hot environmental temperatures differ from people in cooler environments

a) higher critical temperature
b) lower critical temperature
c) higher blood volume
d) lower blood volume

a higher critical temperature blood volume has nothing to do with it so you can eliminate those answers that leaves you with a or b and the question is asking about people that are acclimatized to hot temperatures compare to those in low temperatures therefore the only answer between a and b it would be is a