Definition: You are given a question on virology. You are also given 4 answer options (associated with "A", "B", "C", "D"), out of which only one is correct. You need to answer the question by selecting the correct option. You should only answer with the choice letter, not the whole answer.
Input: How is next generation sequencing (NGS) most often used?
(A)To identify a newly discovered virus (B)To search for drug resistant mutants (C)To identify quasi species viruses (D)Cannot be used

D