Research has demonstrated that loneliness ____.

A) has no effect on the immune system
B) strengthens the immune system (in preparation for battling disease)
C) weakens the immune system
D) strengthens men's immune systems but weakens women's immune systems

Research has shown that loneliness can have a negative impact on health, including weakening the immune system. This is because social isolation and feelings of loneliness can increase stress and inflammation, leading to a reduced ability to fight off infections.