`C_4` cycle was discovered by

Options

A. Hatch and Slack
B. Calvin
C. Hill
D. Arnon

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks who discovered the C4 cycle.

2. **Recall the Scientists**: The C4 cycle was discovered by scientists named Hatch and Slack.

3. **Understand the Naming**: The C4 cycle is often referred to as the "Hatch and Slack Pathway" in recognition of their discovery.

4. **Explain the C4 Cycle**: The C4 cycle is named for the first stable product formed during the cycle, which contains four carbon atoms.

5. **Identify the First Stable Product**: The first stable product of the C4 cycle is oxaloacetic acid, which is a four-carbon compound.

6. **Differentiate from Other Cycles**: It’s important to note that the C3 cycle, known as the Calvin cycle, was discovered by a different scientist, Calvin.

7. **Conclude the Answer**: Therefore, the correct answer to the question is that the C4 cycle was discovered by Hatch and Slack.

**Final Answer**: The C4 cycle was discovered by Hatch and Slack.

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