Endocarditis is often a consequence of bacteria attached to the heart valves. These microbes are not eliminated by circulating lymphocytes because
A. lymphocytes do not circulate through the heart valves to detect the presence of microbes.
B. Gram-positive microbes don't have an exotoxin surface molecule to trigger an immune response.
C. these microbes become covered in platelets and fibrin which is not recognized as foreign by the immune system.
D. lymphocytes cannot engulf microbes attached to tissue.
Answer: C
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