This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Which of the following does not predispose to leukemia 
Select and explain. 
A. Alcohol, B. Genetic disorder, C. Smoking, D. Chemical exposure
A: Alcohol
Answer: A: Alcohol 
Explanation: Leukemia risk factors
1) General

Gender: Men are more likely to develop CML, CLL and AML than women.
Age: The risk of most leukemias, with the exception of ALL, typically increases with age.

2) Genetics

Family history: First-degree relatives of CLL patients, or having an identical twin who has or had AML or ALL, increases the risk for developing the disease.
Genetic diseases: AML has been associated with Down syndrome, Klinefelter syndrome, Patau syndrome, Fanconi anemia, Bloom syndrome, Ataxia telangiectasia, and Kostmann syndrome, may play a role in the development of leukemia.

3) Smoking

Smoking cigarettes does increase the risk of developing AML

4) Exposures 

Radiation : Exposure to high-energy radiation (e.g., atomic bomb explosions) and intense exposure to low- energy radiation from electromagnetic fields (e.g., power lines). 
Chemical exposure: Long-term exposure to chemicals like benzene & ethylene oxide is considered to be a risk for leukemia.
Drugs - alkylating agents & topoisomerase II inhibitors increase the risk of AML.

5) Previous Cancer Treatment

Certain types of chemotherapy and radiation therapy for other cancers are considered leukemia risk factors.