What elements are in hydroxyapatite, ca5(po4)3oh, a major compound in human bones and teeth?

Hydroxyapatite refers to one of the prime components of and an important element of usual teeth and bone. It forms the matrix of teeth and mineral of the bone. It is the hydroxyapatite molecule that gives the teeth and bones their rigidity. These molecules can combine together to produce microscopic clumps.  

About seventy percent of the bone comprises of the inorganic mineral hydroxyapatite that comprises calcium carbonate, calcium phosphate, calcium hydroxide, calcium fluoride, and citrate.  

i believe the answer is c

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."