A nurse who has recently withdrawn from friends and family meets with a counselor to develop stress management techniques. The counselor should explain that social support improves the integrity of which of the following body systems?

A. Social support has a direct positive effect on the immune system. Strong social connections reduce stress, which in turn lowers levels of stress hormones such as cortisol that can suppress immune function. Clients with adequate social support tend to have improved resistance to infections and better overall immune responses. B. While physical activity can strengthen the musculoskeletal system, social support does not directly influence bone or muscle integrity. Its benefits are more related to emotional and physiological stress modulation rather than structural musculoskeletal health. C. Pulmonary system integrity is primarily affected by factors like smoking, respiratory infections, and exercise. Social support does not have a direct physiological effect on lung function, though indirectly it may influence behaviors that affect pulmonary health.