All viruses

Options

A. contain only DNA
B. contain only RNA
C. contain only protein
D. are susceptible to lipid solvents

Answer

To solve the question "All viruses," we need to analyze the characteristics of viruses based on the information provided.

### Step-by-Step Solution:

1. **Understanding Virus Composition**:
- All viruses contain nucleic acids, which can either be DNA or RNA, but not both. This is a fundamental characteristic of viruses.
- In addition to nucleic acids, all viruses have a protein coat known as a capsid that protects the nucleic acid.

2. **Types of Nucleic Acids**:
- Viruses can have either single-stranded or double-stranded nucleic acids. This means that some viruses may contain single-stranded RNA, while others may contain double-stranded DNA.

3. **Presence of Lipid Envelopes**:
- Some viruses have an outer lipid envelope made of fat and protein molecules. This envelope is not present in all viruses but is a characteristic of certain types of viruses.

4. **Protein Presence in Viruses**:
- Regardless of the type of nucleic acid (DNA or RNA), all viruses have proteins. These proteins are essential for the virus's structure and function, including the ability to infect host cells.

5. **Analyzing the Options**:
- The options given are:
1. Contain only DNA
2. Contain only RNA
3. Contain only protein
4. Are susceptible to lipid solvents
- Based on our analysis, we can see that while viruses contain nucleic acids (DNA or RNA) and proteins, they do not contain only one type of nucleic acid or only proteins. However, proteins are a universal component of all viruses.

6. **Conclusion**:
- The most accurate statement regarding all viruses is that they contain proteins. Therefore, the correct answer is **"contain only proteins."**

### Final Answer:
- The correct answer is: **Contain only proteins.**