1. Anorexia is a disease that causes the person to stop eating due to an intense fear of gaining weight, causing the loss of vital nutrients to the scalp and, therefore, hair loss and brittle hair. So the answer is A. brittle hair.
2. Bulimia is a disease associated to the intense fear of gaining weigh too, but in this case the person purges out all the food they have eaten, causing the veins of the esophagus (which are usually thinner than the ones from the rest of the body) to torn due to too many vomiting episodes. So the answer is D. torn esophagus.
3. Smoking leads the person to consume smoke from tobacco, which is carcinogenic (it can cause cancer) and can seriously affect the mouth as it is through where the smoke comes inside the body. So the answer is C. mouth cancer.
4. Alcohol use directly affects the liver, because the liver is responsile for breaking down alcohol but sometimes there is just too much to break down and it can cause damage to the organ. As cirrhosis is a disease of the liver commonly associated to alcohol use, the answer is B. cirrhosis.
Therefore, the final answer is 1-A, 2-D, 3-C and 4-B.