What type of antigens are found on the surface of red blood cells of a person with type AB blood?

A. Mononuclear phagocytic system: that system (macrophages/monocytes) performs cellular phagocytosis, not the physical barriers listed.
B. Chemical barriers: some secretions (tears, saliva) contain chemical antimicrobials, but the items listed (mucus, hair) are primarily physical/mechanical barriers.
C. Adaptive defenses: adaptive defenses are specific immune responses (antibodies, T cells), not the nonspecific physical barriers listed.
D. Mechanical barriers: mucus, hair, and the physical flow of tears/saliva act as mechanical/physical barriers that trap or remove pathogens before they invade.

A. Absorbing fat from ingested food: saliva does not absorb fat; lipid processing occurs later (emulsification by bile, digestion by lipase).
B. Breaking food into smaller pieces: Incorrect (partly true) -mastication (teeth and jaw) breaks food down; saliva lubricates and moistens but does not mechanically triturate alone.
C. Beginning the chemical digestion of carbohydrates: saliva contains salivary amylase, which begins starch digestion into smaller sugars.
D. Cleansing the esophagus: saliva helps cleanse the mouth and aids swallowing, but it does not “cleanse the esophagus” as a primary function.