Single-Gene disease :

A) Are affected by lifestyle behaviors
B) Occur when one gene has a harmful mutation
C) Include cardiovascular disease and cancer
D) Are caused when a person inherits a single chromosome

Answerconsultation report, patient correspondence, and informed consent forms;

The answer you're looking for is washing your hands. "at this late date, we all expect our doctors to wash their hands before examining us or performing an operation in order to prevent the spread of infection. surprisingly, physicians did not begin to acknowledge the lifesaving power of this simple act until 1847.it was then that dr. semmelweis began exhorting his fellow physicians at the famed vienna general hospital (allgemeines krankenhaus) to wash up before examining women about to deliver babies. his plea was far more than aesthetic; it was a matter of life and death and to prevent a deadly malady known as “childbed” or puerperal (from the latin words for child and parent) fever." 

The answer would be    hot or cold holding temperatures of potentially hazardous food.