Correct Response: D. Each of the listed factors helps determine when, where, and how communicable diseases may spread and the frequency at which these diseases may occur. In other words, they help determine the incidence and prevalence of emerging diseases. Diseases that are degenerative (A) cause body tissues to break down over time and can be caused by many different genetic and/or environmental factors, not necessarily by transmission from organism to organism. Chronic diseases (B) are conditions that are long in duration and tend to develop over time. The information presented does not address how to detect and manage chronic diseases. Although the provided information does concern communicable diseases, or diseases that can be spread by contact (C), it does not address how to treat these diseases once an organism has become ill.
