Sentence Correction (SC) | Bloodletting, the withdrawal of small quantities

Bloodletting, the withdrawal of small quantities of blood from a patient,as a procedure to prevent or cure illnesses, it was commonly performed by physicians until the late 19th century when they realized that it caused more harm than good.

A. as a procedure to prevent or cureillnesses, it was commonly performed(Lack of main verb in the sentence)
B. as a commonly performed procedure to prevent or cure illnesses(same as A)
C. was a commonly performed procedure to prevent or cure illnesses
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