Which structure represents the body's first line of defense against inflection?

The body's first line of defense against infection is primarily represented by the skin and mucous membranes. The skin acts as a physical barrier, preventing pathogens from entering the body, while mucous membranes line various cavities and secrete mucus, trapping pathogens and facilitating their removal. Additionally, secretions like saliva, tears, and stomach acid provide chemical defenses against pathogens. Collectively, these structures form a crucial initial defense against infections.