Viroids are

Answer: Option C

Viroids are ss & circular.
Viroids are small single-stranded, circular RNAs that are infectious pathogens.
The first recognized viroid, the pathogenic agent of the potato spindle tuber disease, was discovered, and named by Theodor Otto Diener, a plant pathologist at the U.S. Department of Agriculture's Research Center in Beltsville, Maryland, in 1971.
Viroids only infect plants, and infectious viroids can be transmitted to new plant hosts by aphids, by cross-contamination following mechanical damage to plants as a result of horticultural or agricultural practices, or from plant to plant by leaf contact.