Correct answer: Tobacco
Nicotine is the main mind-affecting chemical substance that is found in the leaves of tobacco. If it is consumed in fewer dosages it is known to increase alertness, reduce anxiety, and raised blood pressure. But if it consumed regularly in high doses it can cause different types of cancer, stroke, infertility, and heart disease etc.
Nicotine that is present in tobacco is known to weaken the immune system of the body and it reduces the ability of the body to fight against cancerous growth.