【单选题】What is the distinction between Crohn's disease and ulcerative colitis?
A.
Crohn's disease produces deeper erosions of the mucosa and occurs throughout the intestines, whereas ulcerative colitis occurs mostly in the rectum.
B.
Crohn's disease results in diverticula, caused by insufficient dietary fiber, whereas ulcerative colitis is caused by the bacterium H. pylori.
C.
Although both diseases are caused by inflammation, Crohn's disease occurs only in the small intestine, whereas ulcerative colitis occurs only in the large intestine.
D.
Crohn's disease is caused by the bacterium H. pylori, whereas ulcerative colitis results from the failure of acid to be neutralized before it reaches the colon.