You have a novel virus that can kill mice when injected into them. This novel virus can transform a non-virulent virus, causing it to become virulent. You want to understand what the transforming factor is made of. You heat kill the novel virus and treat different samples of the heat killed sample with either an RNase, a DNase, or a Proteinase. Of the novel virus uses double-stranded RNA as its genetic material, which treated sample will no longer be capable of transforming the non-virulent strain

The sample treated with RNase

Explanation:

According to this question, a novel virus was found which was capable of killing mice when injected into them and capable of making a nonvirulent virus to be virulent by transforming them.

After heat killing the novel virus, different samples were treated with either an RNase, a DNase, or a Proteinase. If the novel virus uses double-stranded RNA as its genetic material, the sample treated with RNase will no longer be capable of transforming the non-virulent strain. This is because RNase is a catalytic enzyme that degrades RNA, hence, the RNA will no longer be present to transform.

your answer is "the 1950's"