Final answer:
Failure to secrete hCG by an embryo would result in the corpus luteum stopping production of progesterone, leading to the breakdown of the uterine lining and the onset of menses. This would likely cause a miscarriage, hence the embryo would be aborted.
Step-by-step explanation:
If an embryo failed to secrete Human Chorionic Gonadotropin (hCG), several significant events related to pregnancy maintenance would be adversely affected. hCG is a hormone produced by the blastocyst shortly after fertilization and is responsible for signaling the corpus luteum to continue production of progesterone and estrogen. Progesterone is crucial for maintaining the uterine lining (endometrium) and its function in early pregnancy.
Without hCG, the corpus luteum would begin to degrade, progesterone levels would fall, leading to the disintegration of the uterine lining. This process ultimately results in the onset of menses, which would likely lead to the loss of the implanted embryo, effectively resulting in a very early miscarriage or what is often termed a chemical pregnancy. Therefore, the correct answer to the student's question is (d) The embryo would be aborted.