Need help w/this seemingly simple question

[mariposas905]

Can someone explain why the answer to this question (B/B Section Bank, Passage 3, Question #19) is A? I'm so confused...I feel like it's simple but I just don't get it

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[sapientnarwhal]

viral RNA is reverse transcribed to DNA, inserted into genome, then transcribed to the given mRNA sequence. If + is sense and - is antisense, then the viral RNA is +, DNA is -, and mRNA is +.

Note that retroviruses are + sense RNA viruses that integrate into host cell genome.