Question about Viruses

[hiflora]

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A question in TPR on Microbiology (Chapter 6 for the new addition) was about viruses. It asked,

Which of the following statements concerning viruses is true?

The answer was: A virus with an RNA genome must code for an RNA-dependent RNA polymerase.

I first eliminated this answer choice, because my reasoning was that retroviruses, with an RNA genome, uses reverse transcriptase or RNA-dependent DNA polymerase rather than RNA-dependent RNA polymerase to copy their genome. Am I missing something here about retroviruses?

Thanks in advance.

 

[MrRed]

This is strictly classification parameters they are asking about -- an RNA virus can only be classified as such if it uses no DNA intermediates in its life cycle.
A virus that begins with RNA and at some point uses a DNA intermediate is classified as a retrovirus -- which is a distinct class from an RNA virus.

 

[MCATforsale1]

A positive sense RNA virus does create a replicase (RNA Polymerase), but doesn't the negative sense RNA virus carry an RNA polymerase? No need to code for it.