The various types of depression have different causes as well as different levels of severity. Which of the follovwing best describes clinical depression? A. a feeling of overwhelming sadness that usually follows a traumatic event B. a medical condition that may ocCur due to a chemical imbalance in the brain C. alternate feelings of extreme happiness and extreme sadness​

B

Explanation:

exposure to hazardous carcinogens and toxic substances can cause breathing problems, such as copd and various types of cancer. it also increases the risk of heart attacks and strokes and has serious (but no less unattractive) side effects, such as aging, yellow teeth, a terrible smell and damage to the vocal cords.

answer(b) keep oxygenated and deoxygenated blood separate;