The extremely large ($1000\ \text{nm}$) Pandoraviruses discovered in Chile and Australia are classified as viruses because they are unable to copy their own genome and cannot produce proteins. They also possess key structural characteristics in common with other viruses. What are the key structural characteristics of viruses?
- A1, 2 and 3
- B1, 2 and 4
- C1 and 3 only
- D2 and 4 only