What is homeostasis?
an organism that obtains energy from the sun
an organism that obtains energy from another organism
maintaining stability in an organism's internal environment
a process that produces an exact copy of a parent

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.