50 對於48歲無大腸癌家族史之女性，最適當的大腸癌篩檢方式為：
(A) Flexible sigmoidoscopy every year beginning at age 50
(B) Fecal occult blood testing every 3 years beginning at age 40
(C) Air-contrast barium enema every 2 years beginning at age 50
(D) Fecal occult blood testing every 1- 2 years beginning at age 50, if positive, colonoscopy is indicated
(E) Colonoscopy every 5 years beginning at age 45