A gene family that codes for various hormone receptors has been accumulating nucleotide ubstitutions at a rate of 0.4 per million years. On average, there have been 60 substitutions between the common ancestor of this gene family and each of the various living forms of this gene. Based on these figures, this hormone receptor gene family likely originatedmillion years ago. a. 15 b. 24 c. 75 d. 150 e. 300
