The luteal phase
a. is where the body prepares for pregnancy
b. is when the egg reaches maturation and is ovulated
c. ends with the rise of estrogen levels
d. b and c
e. a, b and c

a. where the body prepares for pregnancy

Explanation:

Menstrual cycle has 4 phases:

a. Menstrual phase: Menstrual flow occurs during this phase i.e the uterine endometrium sheds or breaks down. It occurs for around 4-5 days in human females.

b. Follicular phase: Follicular growth occurs in the ovaries, i.e. primary follicle develops into secondary and then tertiary and then finally into mature graffian follicle. Follicular growth is stimulated by FSH hormone. Estrogen level rise during this period and cause the LH surge. Estrogen also repairs the endometrium in uterus.

c. Ovulatory phase: LH surge causes the ovulation i.e. the mature graffian follicle ruptures and secondary oocyte is released.  

d. Luteal phase: The remnants of graffian follicle forms the corpus luteum, which is also called yellow body due to yellow lutein pigment. Progesterone hormone is produced by the corpus leuteum along with small amounts of estrogen. Progesterone produced during luteal phase in ovaries maintains the endometrium in uterus for pregnancy.  

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