What is the main function of the placenta?

a) To produce and secrete hormones that modulate maternal metabolism, mammary gland development, maternal behavior, fetal development, and contribute to maintaining pregnancy.
b) To protect the fetus from all viruses and bacteria that could infect it.
c) To produce and secrete hormones that modulate fetal metabolism, mammary gland development, fetal behavior, maternal development, and contribute to maintaining pregnancy.