Autotrophic nutrition is the process by which autotrophic plants consume substances from external sources and convert them into _______

Explanation

**Step-by-Step Solution:**

1. **Understanding Autotrophic Nutrition**: Autotrophic nutrition is a process used by autotrophic organisms, primarily green plants, to synthesize their own food.

2. **Sources of Substances**: These plants consume substances from external sources, mainly carbon dioxide (CO2) from the air and water (H2O) from the soil.

3. **Role of Sunlight**: The process requires sunlight, which provides the energy necessary for the chemical reactions involved in food production.

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