As we take a shower, the water feels cooler than when we first entered the shower, so

Question:

As we take a shower, the water feels cooler than when we first entered the shower, so we turn up the temperature. Why is that?
(A) It takes time for the water to heat up due to the pipes.
(B) Our body heats up, so the water feels cooler.
(C) We have to get used to the feel of the hot water.
(D) The water in the pipes cools down with time, so a hotter water is needed.