Protons `(as NADH, FADH_(2))` taking par in oxidative phosphorylation enter mitochondira as

Options

A. OAA
B. Acetyl-CoA
C. Pyruvic acid
D. Acetaldehyd

Answer

### Step-by-Step Solution:

1. **Understanding the Context**: The question asks about the entry of protons (in the form of NADH and FADH2) into the mitochondria during oxidative phosphorylation. This process is a part of cellular respiration, which occurs in aerobic conditions.

2. **Identifying the Key Processes**: In aerobic respiration, there are three main stages:
- Glycolysis: This occurs in the cytoplasm and breaks down glucose into pyruvate, producing NADH and FADH2.
- Krebs Cycle (Citric Acid Cycle): This occurs in the mitochondria and further processes pyruvate, generating more NADH and FADH2.
- Electron Transport Chain (ETC) and Oxidative Phosphorylation: This is where NADH and FADH2 donate electrons to the ETC, leading to ATP production.

3. **Entry of Pyruvate into Mitochondria**: The protons carried by NADH and FADH2 are generated during glycolysis and the Krebs cycle. Pyruvate, which is the end product of glycolysis, enters the mitochondria to be converted into Acetyl-CoA before entering the Krebs cycle.

4. **Final Answer**: The protons (as NADH and FADH2) that participate in oxidative phosphorylation enter the mitochondria as **pyruvate**.