Use the following information to answer the next question.

Atlantic salmon (Salmo salar) are raised commercially in fish pens on the Pacific coast of Canada. Genetically altered Atlantic salmon have been developed for commercial use. If some of the Atlantic salmon escape their pens, hybridization could occur with native (Pacific) salmon stocks. Eventually, the original salmon stocks could disappear. One way to address this concern is to sterilize the captive fish. Sex reversal in female salmon can be induced. Sex-reversal of female fish produces a fish with female sex chromosomes and a male reproductive tract. Sex-reversed females can be used to produce sperm with only X chromosomes. There sperm fertilize eggs from normal females, and the fertilized eggs are then treated with heat or pressure shock to induce triploidy (3n). This creates a population of sterile female fish for commercial markets. Male reproductive tract development in fish, as in humans, normally occurs because a _______.

A. single X chromosome stimulates testosterone secretion by the gonads
B. Y chromosome stimulates testosterone secretion by the gonads
C. Y chromosome inhibits estrogen secretion by the gonads
D. single X chromosome inhibits estrogen secretion by the gonads