The last to receive electrons in electron transpo system is:

**Core Concept**
The electron transport system (ETS) is a critical component of cellular respiration, responsible for generating the majority of ATP during oxidative phosphorylation. The ETS consists of a series of protein complexes and electron carriers that facilitate the transfer of electrons from high-energy molecules to oxygen, ultimately resulting in the production of ATP.

**Why the Correct Answer is Right**
The correct answer is **Complex IV (Cytochrome c Oxidase)**. This enzyme is the last to receive electrons in the ETS, as it directly reduces oxygen to water. Complex IV is located in the mitochondrial inner membrane and consists of a heme group and a copper center, which facilitate the transfer of electrons to oxygen. The reduction of oxygen to water is a critical step in the ETS, as it allows the energy from the electrons to be coupled to the production of ATP.

**Why Each Wrong Option is Incorrect**
* **Option A:** Complex I (NADH Dehydrogenase) is incorrect because it is the first enzyme in the ETS to receive electrons from NADH, not the last.
* **Option B:** Complex II (Succinate Dehydrogenase) is incorrect because it is a part of both the ETS and the citric acid cycle, but it is not the last to receive electrons in the ETS.
* **Option D:** ATP Synthase is incorrect because it is not an enzyme that receives electrons, but rather a protein that uses the energy from the ETS to produce ATP.

**Clinical Pearl / High-Yield Fact**
The electron transport system is a critical component of cellular respiration, and disruptions to the ETS can lead to a range of diseases, including mitochondrial myopathies and neurodegenerative disorders.

**Correct Answer: C. Cytochrome c Oxidase**