What are the main functions of estrogen and progesterone during the
follicular and luteal phases?

Estrogen dominates the follicular phase while progesterone dominates the luteal phase with both functioning  to enable the menstrual cycle.

Explanation:

The function of estrogen present in blood stimulates the endometrium and myometrium within the uterus to grow. The effect of estrogen is also to promotes production of progesterone reception by cells present in the endometrium, resulting in the priming to the late proliferative phase as well as the luteal phase of the endometrium.

The function of the progesterone is to convert the proliferative endometrium, primed by the estrogen into one that secretes which is blastocyst receptive.

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.