Decomposition of organic nitrogen of dead plants and animals into ammonia is called______.

Options

A. (a) nitrification
B. (b) nitrate reduction
C. (c) `N_(2)` fixation
D. (d) ammonification

Explanation

**Step-by-Step Solution:**

1. **Understanding the Process**: The question asks about the decomposition of organic nitrogen found in dead plants and animals. This process involves breaking down organic matter to release simpler compounds.

2. **Identifying the Key Term**: The key term we are looking for is the specific process that converts organic nitrogen into ammonia.

3. **Recognizing the Role of Microorganisms**: This decomposition is primarily carried out by microorganisms, specifically decomposers like bacteria and fungi. They play a crucial role in breaking down organic matter.

4. **Defining the Process**: The specific process that converts organic nitrogen from dead plants and animals into ammonia is known as **ammonification**.

5. **Final Statement**: Therefore, the decomposition of organic nitrogen of dead plants and animals into ammonia is called **ammonification**.

6. **Selecting the Correct Option**: Among the given options, the correct answer is option D: **ammonification**.

**Final Answer**: The decomposition of organic nitrogen of dead plants and animals into ammonia is called **ammonification** (Option D).

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