What are the body's natural barriers against pathogens? Choose the THREE correct answers.

A. mucous membranes
B. nails
C. skin
D. stomach acid

A48-year-old male presents with an 8-day history of productive cough, subjective fevers, and malaise. he is otherwise healthy without any active medical problems. he is a social drinker of alcohol, and denies any tobacco or drug use. on physical examination, the patient is alert and oriented. his temperature is 100.4 0 f, pulse rate is 56, respiratory rate is 18, and blood pressure is 133/64. heent is within normal limits and a chest exam has diffuse expiratory wheeze with decreased sounds to the right lower lung fields. blood labs reveal wbc 14.4, hgb 11.3, plt 233, alt 65, ast 102, and po 4 2.1. a chest x-ray reveals a dense consolidation with bulging fissures. based on these findings, what is the most likely pathogen affecting this patient?