**Core Concept**
Pancreatic carcinoma is a type of pancreatic cancer that originates in the exocrine glands of the pancreas. Early detection of pancreatic carcinoma is crucial for improving patient outcomes, but it remains a challenging task due to its non-specific symptoms and lack of early warning signs. The most sensitive investigation for pancreatic carcinoma would ideally be a non-invasive imaging modality that can detect the tumor at an early stage.

**Why the Correct Answer is Right**
The most sensitive investigation of pancreatic carcinoma is the Endoscopic Ultrasonography (EUS). EUS combines high-frequency sound waves with endoscopy to produce detailed images of the pancreas and surrounding tissues. It can detect small pancreatic tumors, evaluate tumor invasion, and assess lymph node involvement, making it an excellent tool for early diagnosis and staging of pancreatic carcinoma. The EUS has a high sensitivity and specificity for detecting pancreatic tumors, especially when combined with fine-needle aspiration (FNA) for tissue sampling.

**Why Each Wrong Option is Incorrect**
* **Option A:** Computed Tomography (CT) scan is a common imaging modality for pancreatic carcinoma, but it has lower sensitivity compared to EUS, especially for small tumors.
* **Option B:** Magnetic Resonance Imaging (MRI) is not the most sensitive investigation for pancreatic carcinoma, as it may not provide adequate resolution of the pancreas and surrounding tissues.
* **Option D:** Ultrasound is not a suitable option for pancreatic carcinoma, as it has limited sensitivity and specificity for detecting small tumors.

**Clinical Pearl / High-Yield Fact**
When evaluating pancreatic carcinoma, it's essential to remember that EUS is the most sensitive investigation, especially when combined with FNA for tissue sampling. This combination can improve the accuracy of diagnosis and staging, ultimately leading to better patient outcomes.

**Correct Answer: C. Endoscopic Ultrasonography (EUS).**