Which is the fourth in the following sequence of events?

The answer is B. Infective endocarditis usually follows bacteraemia (A) in a patient with some abnormality of the heart valves (C). This is often associated with previous rheumatic fever, although congenital valve anomalies are also involved.

Tonsillectomy (D) is the cause of the bacteraemia, which results in large soft crumbly vegetations on the abnormal valve cusps. The order is C-D-A-B-E.