Answer:
A. Cigarettes — There is no safe smoking option. The one and only safe way to reduce harm would be stop smoking. The effects of Cigarettes on our body are : risks of cancer , heart diseases , stroke , lung diseases , diabetes , breathing problems etc.
B. Alcohol — 355 milliliters of Alcohol is safe for women while 710 millilitres of Alcohol is safe for men. The effects of Alcohol on our body are : Insomnia , Problems with memory and Concentration , Aggressive or Defensive Behaviours , Liver Diseases , Breathing problems , Head pain etc.
C. Marijuana — Less than 40 mg of THC is safe to consume. The effects of Marijuana are : Memory and Concentration Problems, Triggers Anxiety and Depression, Heart Diseases, Lung Diseases, Cancer etc.