Carbon becomes available to crop plants in the form of:

Options

A. elemental carbon
B. carbonates
C. carbon dioxide
D. carbohydrates

Answer

To solve the question "Carbon becomes available to crop plants in the form of:", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Forms of Carbon**: Understand the different forms in which carbon can exist in nature. Common forms include carbon dioxide (CO2), carbon monoxide (CO), organic carbon compounds, and elemental carbon.

2. **Focus on Plant Nutrition**: Recognize that plants primarily absorb carbon from their environment for growth and energy. The main process through which they utilize carbon is photosynthesis.

3. **Understand Photosynthesis**: Recall that during photosynthesis, plants take in carbon dioxide (CO2) from the atmosphere. This gas is essential for the synthesis of carbohydrates.

4. **Carbohydrate Production**: During photosynthesis, plants convert CO2 into glucose (a carbohydrate) using sunlight, water, and chlorophyll. This glucose serves as an energy source for the plant.

5. **Conclusion**: Based on the above points, we can conclude that carbon becomes available to crop plants in the form of carbon dioxide (CO2).

### Final Answer:
The correct answer is carbon dioxide (CO2).

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