Ans.
Human reproduction involves release of sperm (male gamete) and egg (female gamete) and their fusion to form zygote that develops into embryo. In females, an egg is released each month as a part of a monthly cylce, called menstrual cycle. The release of egg is termed as ovulation, in which tiny eggs are send into the fallopian tubes for fertilization.
Hence, the correct answer is 'a). an adult female usually releases an egg from an ovary each month.'
