Which of the following is a common complication of Crohn's Disease?

Fistulas are indeed a common complication associated with Crohn's Disease. This inflammatory bowel disease can lead to abnormal connections between different parts of the intestine or between the intestine and other organs, such as the bladder or skin. The inflammation and ulceration characteristic of Crohn's can directly cause fistula formation as tissues break down and connect in unintended ways.

Fistulas can lead to a range of complications, including infection and abscess formation, which can complicate the management of Crohn's Disease, necessitating careful monitoring and often surgical intervention. The presence of fistulas can significantly affect a patient’s quality of life and require comprehensive medical and sometimes surgical management to treat the underlying disease and maintain intestinal function.

The other options, while they may be seen in gastrointestinal conditions, are not specifically or commonly complications of Crohn's Disease.