Pneumonia and Other Infections Occur at Higher Rates in People

Pneumonia and other infections occur at higher rates in people who have cancer, heart disease, lung disease, or liver disease, which illustrates that

A) infectious diseases are often linked to behavioral risks, such as smoking, poor diet, and alcohol abuse.
B) many people have a disease-prone personality that causes additional infections.
C) genetics plays a strong role in the cause of cancers and diseases.
D) the causes of cancers and diseases are coincidental and unpredictable.