Final answer:
The hormone responsible for maintaining the corpus luteum is c) human chorionic gonadotropin (hCG), which is crucial for the early stages of pregnancy.
Step-by-step explanation:
The hormone that maintains the viability of the corpus luteum is c) human chorionic gonadotropin (hCG).
This hormone is secreted by the outer layer of the blastocyst after a zygote forms and begins to divide. The role of hCG is crucial as it is very similar to luteinizing hormone (LH) and acts to preserve the corpus luteum, enabling it to continue its secretion of progesterone, which is essential for maintaining the early stages of pregnancy. Progesterone prepared the endometrial lining for potential implantation and suppresses the release of GnRH, FSH, and LH, thus maintaining the uterine environment conducive for fetal development.