Which of These Statements Applies to Melanocyte-Stimulating Hormones

Which of these statements applies to melanocyte-stimulating hormones

A) They are responsible for the deposition of melanin in the skin during the process of tanning.
B) They are not present in significant amounts in adult humans.
C) They are present in varying amounts in races of different skin colour.
D) They are important for colour adaptations associated with camouflage in certain lower vertebrates.