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: Identify the most commonly used diagnostic technique in the virus laboratory:
(A)Virus isolation in cell culture (B)Deep sequencing (NGS) (C)Reverse transcriptase (RT) PCR (D)Immuno-serology

B