**Core Concept**
The "double duct" sign is a radiological finding that suggests the presence of a pancreatic divisum, a congenital anomaly of the pancreas where the pancreas is divided into two separate ducts instead of the usual single main pancreatic duct. This anomaly can lead to pancreatitis and other complications.

**Why the Correct Answer is Right**
The "double duct" sign is observed on imaging studies, such as MRI or CT scans, where two separate ducts are visualized arising from the pancreas. This is due to the incomplete fusion of the dorsal and ventral pancreatic buds during embryonic development, resulting in a separate dorsal pancreatic duct that drains pancreatic secretions into the common bile duct. The main pancreatic duct, on the other hand, drains into the duodenum.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the "double duct" sign is not typically associated with choledochal cysts, which are congenital anomalies of the bile duct.
* **Option B:** This option is incorrect because the "double duct" sign is not a characteristic finding in pancreatic cancer, although pancreatic cancer can cause obstruction of the pancreatic duct.
* **Option C:** This option is incorrect because the "double duct" sign is not a feature of pancreatitis, although pancreatitis can be a complication of pancreatic divisum.

**Clinical Pearl / High-Yield Fact**
The "double duct" sign is a key radiological finding that can help diagnose pancreatic divisum, a congenital anomaly that can lead to pancreatitis and other complications.

**Correct Answer:** C. Pancreatic divisum