Which of the following statements about crohn's disease in incorrect

Which of the following statements about crohn’s disease in incorrect

a.Granulomas present frequently

b.it is seprate and distrinct from ulcerative colitis

c.Cigratte smoking is a risk factor

d.Rectum spared in 50% patients with large bowel involvement

ans:d.Rectum spared in 50% patients with large bowel involvement