Final answer:
Viroids are smaller than viruses and consist of single-stranded RNA without a protein coat, known to infect plants. They reproduce only within a host cell, unlike viruses which can contain DNA or RNA and have a protein coat that infects various organisms.
Step-by-step explanation:
The correct statement about viroids is that they are smaller than viruses. Viroids are unique infectious agents composed of a small, circular piece of single-stranded RNA without any protein coat. Unlike viruses, viroids do not encode proteins and cannot reproduce outside a host cell. They are known to infect plants, and as of the current understanding, human diseases have not been associated with viroids. It’s important to differentiate viroids from viruses, as viruses may contain either DNA or RNA but not both, and they have a protein coat called a capsid. Additionally, viruses infect a vast range of organisms including plants, animals, fungi, and bacteria.
The correct statement about viroids is that they are composed of single-stranded RNA particles, making option c) They are smaller than viruses true. Viroids are small, circular RNA particles that are simpler than viruses and do not contain proteins or infect bacteria. They are only found in plants and have not been identified as causing diseases in humans.