Which of the following conditions could make a person more susceptible to infections?

A weakened immune system significantly increases a person's susceptibility to infections because the immune system is responsible for defending the body against pathogens such as bacteria, viruses, and fungi. When the immune system is compromised, whether due to underlying health conditions, medications, or other factors, the body's ability to effectively fight off infections is diminished. This can lead to an increased risk of becoming ill from many types of infectious agents that a healthy immune system would typically manage or eliminate.

High vitamin intake, regular exercise, and good hygiene practices are all beneficial for maintaining and enhancing immune function. High vitamin intake can support various immune responses, regular exercise can improve overall health and immune performance, and good hygiene practices help prevent the introduction of pathogens into the body. Therefore, it is the weakened immune system that stands out as a risk factor for increased susceptibility to infections.