You Are Investigating the Evolutionary History of the Hormone Irisin

You are investigating the evolutionary history of the hormone irisin that was recently discovered in mice.Released by skeletal muscle cells during exercise, it triggers the "browning" of white fat.Based on scientific thinking about the evolutionary history of hormones, it would be reasonable to hypothesize that

A) the hormone is specific to the species of mouse in which it was found.
B) other mammalian species might also produce the hormone, but non-mammalian species are unlikely to produce irisin.
C) the hormone might be produced in other organisms, but only in organisms that have skeletal muscles.
D) irisin might be produced in many different groups of organisms, even organisms such as sponges that lack skeletal muscle cells.
E) the hormone is likely to be produced in unicellular organisms, such as bacteria.