The decomposition of organic compounds, in the presence of oxygen and without the development of odoriferous substances, is called

Options

A. decay
B. `N_(2)`-fixation
C. nitrification
D. denitrification

Explanation

To solve the question regarding the decomposition of organic compounds in the presence of oxygen and without the development of odoriferous substances, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a term that describes the decomposition of organic compounds when oxygen is present and without producing foul-smelling substances.

2. **Analyze the Options**: The options provided are:
- A) Decay
- B) Nitrogen fixation
- C) Nitrification
- D) Denitrification

3. **Define Each Term**:
- **Decay**: This refers to the process of decomposition of organic matter, typically involving the breakdown of complex organic substances into simpler substances in the presence of oxygen. It usually does not produce strong odors.
- **Nitrogen Fixation**: This is the process by which nitrogen in the atmosphere is converted into ammonia or related nitrogenous compounds in soil and water, typically involving bacteria.
- **Nitrification**: This is a microbial process that converts ammonia into nitrites and then into nitrates, also involving bacteria.
- **Denitrification**: This is the process by which nitrates are reduced to nitrogen gas, which is released into the atmosphere, again involving bacteria.

4. **Identify the Correct Answer**: Among the options, "decay" is the only term that specifically refers to the decomposition of organic compounds in the presence of oxygen without the development of foul odors. The other terms (nitrogen fixation, nitrification, and denitrification) are related to nitrogen cycles and do not pertain to the decomposition of organic matter.

5. **Conclusion**: Therefore, the correct answer to the question is **A) Decay**.

### Final Answer:
The decomposition of organic compounds, in the presence of oxygen and without the development of odoriferous substances, is called **Decay**.