Although viruses can have RNA and/or DNA, they do not qualify as living things because:

• A. they respond to external stimuli in the same way as living organisms.
• B. they cannot carry out metabolic processes independently.
• C. they are composed of cells.
• D. they can reproduce without a host cell.

Answer: (B)

Verified step by step guidance

1. Understand the characteristics of living organisms: Living organisms are defined by their ability to carry out metabolic processes independently, reproduce, respond to stimuli, and be composed of cells.
2. Analyze the statement about viruses: Viruses are unique entities that can contain RNA or DNA, but they lack the ability to perform metabolic processes independently. They rely entirely on a host cell for replication and metabolic activities.
3. Evaluate the options provided: Compare each option against the characteristics of living organisms. For example, viruses do not respond to external stimuli in the same way as living organisms, and they are not composed of cells.
4. Focus on the correct answer: The defining feature that disqualifies viruses as living organisms is their inability to carry out metabolic processes independently. This is a key distinction between viruses and living organisms.
5. Conclude the reasoning: Viruses are considered non-living because they depend on host cells for reproduction and metabolism, which violates the criteria for independent life processes.