उत्तर : 3. "न्यूक्लिक एसिड और प्रोटीन"
व्याख्या :

1. Viruses do not find a place in classification because they are not actually considered 'living'.

2. Viruses are non-cellular organisms.

3. The name virus which means poison or poisonous fluid was given by Dmitry Ivanovsky.

4. Viruses cause diseases like mumps, smallpox, shingles and influenza.