Name two organisms whose Symbiotic association leads to nitrogen fixation in root nodules.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for two organisms that form a symbiotic association with plants to facilitate nitrogen fixation in root nodules.

2. **Identifying the Process**: Nitrogen fixation is the process where atmospheric nitrogen (N2) is converted into ammonia (NH3), which plants can use for growth. This process is crucial because atmospheric nitrogen is not directly usable by plants.

3. **Recognizing the Organisms**: The primary organisms involved in this symbiotic relationship are bacteria. Specifically, certain bacteria form nodules on the roots of plants and assist in nitrogen fixation.

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