_____ is highly hazardous to animal health but not plants, this gas does not seem to show adverse effect.

Options

A. CO
B. `CO_(2)`
C. `SO_(2)`
D. `NO_(2)`

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
- The question asks for a gas that is highly hazardous to animal health but does not adversely affect plants.

2. **Identifying the Characteristics of the Gas:**
- The gas in question must be harmful to animals when inhaled but should not have a negative impact on plant health.

3. **Considering Possible Gases:**
- Think about gases that are known to be toxic to animals. Common examples include carbon monoxide, sulfur dioxide, and nitrogen oxides.

4. **Analyzing Carbon Monoxide:**
- Carbon monoxide (CO) is a colorless and odorless gas produced from the incomplete combustion of fuels such as gas, oil, kerosene, wood, and charcoal.
- It is known to be particularly dangerous to animals (including humans) because it can replace oxygen in the bloodstream.

5. **Understanding the Effects on Animals:**
- When animals inhale carbon monoxide, it binds to hemoglobin in the blood more effectively than oxygen, leading to oxygen deprivation (or oxygen starvation) in the body. This can be fatal if exposure is significant.

6. **Effects on Plants:**
- Unlike animals, plants do not have a respiratory system that is affected by carbon monoxide in the same way. Therefore, carbon monoxide does not show adverse effects on plant health.

7. **Final Answer:**
- Based on the analysis, the correct answer to the question is **carbon monoxide**.

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