Answer : 3. "Nucleic acid and protein "
Explanation :

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.