Okay, let's tackle this question. The question is about how many oxygen molecules myoglobin can bind. I remember that myoglobin is involved in oxygen storage in muscles, right? Hemoglobin in the blood carries oxygen, but myoglobin in the muscle cells stores it.

Wait, hemoglobin has four subunits and can bind four oxygen molecules. But myoglobin is a single polypeptide chain with a heme group. I think each heme group can bind one oxygen molecule. So maybe myoglobin only binds one oxygen molecule. Let me confirm.

Yes, myoglobin has one heme group per molecule. So each myoglobin molecule can bind one oxygen. Hemoglobin, on the other hand, has four heme groups. So the answer should be one. The options might be 1, 2, 4, or something else. The correct answer is 1. The other options are for hemoglobin or other structures. For example, hemoglobin's four oxygen bindings might be a distractor. Also, maybe some other proteins have different numbers. But myoglobin is definitely one. Let me make sure about the structure again. Myoglobin is a monomer with one heme, so one oxygen binding site. Yep, that's right.

**Core Concept**
Myoglobin is a monomeric, oxygen-binding protein found in muscle cells. Unlike hemoglobin, which has four subunits, myoglobin contains a single heme group capable of binding one oxygen molecule, facilitating oxygen storage in muscle tissue during high metabolic demand.

**Why the Correct Answer is Right**
Myoglobin consists of a single polypeptide chain with one heme prosthetic group. The heme iron (Fe²⁺) binds reversibly to one oxygen molecule via a coordination bond. This single binding site allows myoglobin to act as an oxygen reservoir in muscle cells, releasing oxygen when partial pressure drops during intense activity.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect. This suggests myoglobin binds multiple oxygen molecules, which is false. Myoglobin lacks the quaternary structure needed for cooperative binding.
**Option B:** Incorrect. Two oxygen molecules would imply two heme groups, which myoglobin does not possess.
**Option C:** Incorrect. Four oxygen molecules correspond to hemoglobin’s tetrameric structure, not myoglobin’s monomeric structure.

**Clinical Pearl / High-Yield Fact**
Myoglobin’s single oxygen-binding site gives it a higher affinity for oxygen than hemoglobin, enabling it to extract oxygen from blood even at low partial pressures. This is why myoglobin is critical for diving mammals and skeletal muscle endurance.

**Correct Answer: C. 1**

✓ Correct Answer: C. 1