Final answer:
Viroids are plant pathogens that consist of single-stranded, circular RNA without a protein coat and parasitize plants, not animals, bacteria, or fungi.
Step-by-step explanation:
Viroids are a unique group of pathogens distinct from viruses, with a primary impact on the plant kingdom. Unlike viruses, viroids consist of small, single-stranded, circular RNA particles that lack a protein coat or capsid. As obligate parasites, they require a host for replication, and this host is most commonly a plant. This is supported by the fact that viroids are plant pathogens and human diseases caused by viroids have yet to be identified. They cause various plant diseases and can have significant economic impacts on agriculture.
Therefore, the group of organisms that viroids are most likely to parasitize is C. Plants. This aligns with the host range concept, which indicates that many pathogens, including viruses and viroids, are generally specific to certain hosts. Viroids have been confirmed as the causative agent of diseases in various plant species, and their identification typically involves molecular techniques like RNA analysis.