Mesoderm
Mesoderm is the primary germ layer that is responsible for producing both blood and phagocytic brain glial cells.
The mesoderm is the middle of the three germ layers that appears in the third week of embryonic development. The mesoderm is responsible for the formation of various body structures such as epithelia of blood vessels, blood, muscle, bone, phagocytic brain glial cells, lymphatic vessels, adrenal cortex, notochord, and bone marrow.
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.'