**Core Concept**
Chymotrypsinogen is a zymogen (inactive precursor) of the digestive enzyme chymotrypsin, which plays a crucial role in the breakdown of proteins in the small intestine. The conversion of chymotrypsinogen to chymotrypsin is a critical step in the activation of digestive enzymes.

**Why the Correct Answer is Right**
Chymotrypsinogen is converted to chymotrypsin by the enzyme enterokinase (also known as enteropeptidase), which is secreted by the cells lining the duodenum. Enterokinase cleaves the activation peptide from chymotrypsinogen, resulting in the formation of chymotrypsin. This activation process is essential for the initiation of protein digestion in the small intestine.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because there is no evidence to suggest that chymotrypsinogen is converted to chymotrypsin by trypsin.
* **Option B:** This option is incorrect because pepsin is an enzyme involved in protein digestion in the stomach, not in the activation of chymotrypsinogen to chymotrypsin.
* **Option D:** This option is incorrect because the pancreas does produce chymotrypsinogen, but it is not responsible for its conversion to chymotrypsin.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the activation of digestive enzymes, including chymotrypsinogen to chymotrypsin, is a critical step in the breakdown of proteins in the small intestine. Impaired activation of these enzymes can lead to malabsorption of essential nutrients.

**Correct Answer: C. Enterokinase (enteropeptidase)**