**Core Concept**
In post-hepatic jaundice, bilirubin accumulation occurs due to obstruction of the bile duct, preventing conjugated bilirubin from entering the intestine. The liver's ability to conjugate bilirubin is crucial in this context.

**Why the Correct Answer is Right**
The correct answer, **C. The conjugation process of bilirubin in liver remains operative without any interference**, is accurate because the liver's conjugation process for bilirubin, mediated by the enzyme UDP-glucuronosyltransferase (UDP-GT), remains intact in post-hepatic jaundice. This process involves the conversion of unconjugated bilirubin to conjugated (direct) bilirubin, which is water-soluble and can be excreted into the bile. The liver's ability to conjugate bilirubin without interference explains why the concentration of conjugated bilirubin is higher than that of unconjugated bilirubin in post-hepatic jaundice.

**Why Each Wrong Option is Incorrect**
* **Option A:** Increased destruction of red blood cells would lead to an increase in unconjugated bilirubin levels, not a specific increase in conjugated bilirubin.
* **Option B:** Bile stones would actually obstruct the bile duct, preventing conjugated bilirubin from entering the intestine, which contradicts the premise of post-hepatic jaundice.
* **Option D:** Increased UDP-glucuronosyltransferase activity would facilitate conjugation, but the liver's existing conjugation process is not the primary reason for the higher concentration of conjugated bilirubin in post-hepatic jaundice.

**Clinical Pearl / High-Yield Fact**
In post-hepatic jaundice, the liver's conjugation process remains intact, but the obstruction of the bile duct prevents conjugated bilirubin from being excreted into the intestine. This distinction is crucial for understanding the pathophysiology of post-hepatic jaundice and differentiating it from other forms of jaundice.

✓ Correct Answer: C. The conjugation process of bilirubin in liver remains operative without any interference.