Snakes shed their outermost layer of skin regularly. which characteristic of life is this action an example of? excretion growth homeostasis nutrition reproduction

It seems to either be homeostasis so the snake may regulate its state of being like how a person will take off their coat when it gets too warm or growth where the snake sheds its skin to prepare for growth. From what I can tell, the answer can't be excretion, reproduction, or nutrition. As the skin, gave no initial nutritional value so that eliminates excretion and nutrition. The snake isn't giving birth to other snakes during this process so that eliminates Reproduction.

the answer to the blank provided is “an autosomal gene that is required for the expression of genes on the x chromosome”.

testis-determining factor, abbreviated as td, which is more popularly known as sex-determining region y or sry protein, is a dna-binding protein or  gene-regulatory protein/transcription factor, encoded by the  sry gene. it is the gene responsible for the initiation of male gender determination in humans.