16. which of the following are gametes?
a. sperm and embryo
b. ovaries and testes
© sperm and estrogen
d. egg cell and sperm

D. egg cell and sperm

basically gametes make babies and those are the two things you need to create one.

Gametes are the cells used during sexual reproduction to produce a new individual organism or zygote. The male gamete, sperm, is a smaller, mobile cell that meets up with the much larger and less mobile female gamete, egg or ova. Both sperm and egg are only haploid cells. They only carry half of the chromosomes needed.

Explanation:I am the answer giver and this is your answer.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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