Which factor is NOT associated with an increased risk of infection?

The correct answer indicates that exercise frequency is not associated with an increased risk of infection. In fact, regular moderate exercise is generally linked to a stronger immune system and can be beneficial in reducing the risk of infections. Physical activity improves circulation and helps to flush bacteria out of the lungs and airways. It also enhances the immune response and has been shown to decrease inflammation, all of which contribute positively to overall health and resilience against infection.

On the other hand, age, sex, and nutrition are all factors that can significantly influence a person's susceptibility to infection. For instance, the elderly often have a more weakened immune response, making them more vulnerable. Sex can also play a role, as hormonal differences may affect immune function. Nutrition is crucial; malnutrition can impair the immune system, leading to a higher risk of infections. Thus, while factors like age, sex, and nutrition can increase the likelihood of infection, exercise frequency does not have the same negative correlation.