First `CO_(2)` release in aerobic respiration occurs during :-

Options

A. 3-PGAL formation
B. Pyruvic acid formation
C. Acetyl CoA formation
D. `alpha`-Ketoglutaric acid formation

Answer

To determine when the first CO₂ is released during aerobic respiration, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Aerobic Respiration**: Aerobic respiration occurs in the presence of oxygen and involves several stages: glycolysis, the link reaction (also known as pyruvate oxidation), and the Krebs cycle.

2. **Identify the Stages**:
- **Glycolysis**: This is the first stage where glucose (a 6-carbon molecule) is broken down into two molecules of pyruvic acid (3-carbon molecules). No CO₂ is released during this stage.
- **Link Reaction**: This stage occurs after glycolysis. The pyruvic acid (3-carbon) is converted into acetyl coenzyme A (2-carbon). During this conversion, one carbon is released in the form of CO₂.

3. **Determine the First CO₂ Release**: The first CO₂ release occurs during the link reaction when pyruvic acid is converted to acetyl coenzyme A. This is the critical step where one carbon atom is removed from the 3-carbon pyruvic acid, resulting in the release of CO₂.

4. **Evaluate the Options**:
- Option A: 3-PGAL formation - Incorrect, as this occurs during glycolysis.
- Option B: Pyruvic acid formation - Incorrect, as this is still part of glycolysis.
- Option C: Acetyl coenzyme A formation - Correct, as this is where the first CO₂ is released.
- Option D: Alpha-ketoglutaric acid formation - Incorrect, as this occurs later in the Krebs cycle.

5. **Conclusion**: The first CO₂ release in aerobic respiration occurs during the formation of acetyl coenzyme A in the link reaction.

### Final Answer:
The first CO₂ release in aerobic respiration occurs during **Option C: Acetyl coenzyme A formation**.