Final answer:
Viruses can be either DNA or RNA viruses, but not both at the same time. DNA viruses replicate by transcribing RNA from their DNA genome, while RNA viruses may reverse transcribe RNA into DNA. The correct answer is that both DNA and RNA viruses exist.
Step-by-step explanation:
Amoebic dysentery is not caused by viruses, but the question seems to be regarding the composition of viruses in general. To clarify, viruses that cause various diseases can have either DNA or RNA as their genetic material, but not both simultaneously. DNA viruses belong to groups like Group I and have DNA as their genome and reproduce by transcribing RNA from their DNA genome. On the other hand, RNA viruses, such as those in Group VI, use RNA as their genome and can reverse transcribe their genome into DNA for replication. Therefore, the correct answer to the question "Which viruses are DNA or RNA viruses?" is c) Both DNA and RNA viruses, as viruses can have either DNA or RNA, but each individual virus only contains one type of nucleic acid.