**Core Concept**
Albumin is a major plasma protein synthesized in the liver, playing a crucial role in maintaining plasma oncotic pressure. It is used as a marker for various clinical conditions, including liver disease, nephrotic syndrome, and malnutrition. The measurement of albumin is essential in assessing the nutritional status and liver function of patients.

**Why the Correct Answer is Right**
The correct answer is related to the measurement of plasma volume. 1-125 labelled albumin is used to measure the plasma volume, as it remains in the vascular space and does not get distributed into the interstitial space. This is because albumin is a large molecule that is retained within the blood vessels. The measurement of plasma volume is essential in various clinical conditions, such as in the assessment of shock, burns, and liver disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not relate to the measurement of albumin. Other proteins, such as globulins, may be used for different purposes, but they are not directly related to the measurement of plasma volume.
* **Option B:** This option is incorrect because it is not a specific application of albumin measurement. While albumin is used as a marker for various clinical conditions, the measurement of plasma volume is a specific application that is not related to this option.
* **Option D:** This option is incorrect because it is not a recognized application of albumin measurement. While albumin is used as a marker for nutritional status, the measurement of plasma volume is a specific application that is not related to this option.

**Clinical Pearl / High-Yield Fact**
One important clinical application of albumin measurement is in the assessment of liver dysfunction. Albumin is synthesized in the liver, and its levels decrease in liver disease. Therefore, it is essential to measure albumin levels in patients with suspected liver disease.

**Correct Answer:** C.