An incident in Donora, Pennsylvania, led to which action?

banning the burning of coal

enacting air pollution laws

banning the use of CFCs

conducting cost-benefit analyses

answer: blah

explanation:

bc blah

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

"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."