Ddt was widely used as a pesticide for 20 years. its use was banned after studies showed severe side effects were evident in humans, the environment, and animals as a result of ddt. which reason best explains why the side effects of ddt were so harmful? a. ddt kills insects and other pests. b. ddt decomposes. c. ddt was genetically engineered. d. ddt bioaccumulates.

d. DDT bioaccumulates

Explanation: Bioaccumulation is the entry of pollutants such as metals into a food chain. Substances such as perchlorinated biphenyls (PCBs), (DDT) are potentially dangerous over a period of time as it accumulates. DDT concentration is calculated in parts per million.

Biomagnification on the other hand is the build up of toxins in a food chain. An increase in the trophic level in a food chain results to an increase in the amount of toxic build up.

"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."

a and c are the answeres