Which of the following lists correctly identifies the three main criteria used to classify viruses?

• A. Type of nucleic acid, symmetry of the capsid, presence or absence of an envelope
• B. Host range, method of replication, pathogenicity
• C. Size, shape, ability to cause disease
• D. Cell wall composition, metabolic pathway, motility

Answer: (A)

Verified step by step guidance

1. Understand that virus classification is based on structural and genetic characteristics rather than traits like metabolism or motility, which viruses lack.
2. Recall that the three main criteria used to classify viruses include the type of nucleic acid they contain (DNA or RNA), which is fundamental to their identity and replication.
3. Recognize that the symmetry of the capsid, which is the protein shell enclosing the viral genome, is another key classification criterion; common symmetries include icosahedral and helical.
4. Consider the presence or absence of an envelope, which is a lipid membrane surrounding some viruses, influencing their infectivity and stability.
5. Compare the given options and identify the list that includes these three criteria: type of nucleic acid, symmetry of the capsid, and presence or absence of an envelope.