Answer:
The correct answer is B. May involve enhancement or impairment of the immune system.
Explanation:
Stress for a shorter time period can be lead to an enhancement of the immune system as it increases the essential alert system of the body and regulates it.
However, stress for a longer period reduces the ability of the immune system to fight with antigens that can lead to infection and suppressing of the lymphocytes.
Thus, the correct answer is B.
The drug is most likely going to be tobacco, it is well known that if you smoke one of the side effects is respiratory issues
Definitely not B or C so it has to be either A or D.
