How does fiber intake decrease the risk for cancer?

a.) It protects the intestines by reducing their exposure to toxins.
b.) It increases the levels of estrogen, thus decreasing the risk for endometrial and breast cancer.
c.) It mimics the action of estrogen and blocks angiogenesis.
d.) It increases the levels of insulin, thus decreasing the risk for pancreatic cancer.
e.) It acts as an antioxidant and neutralizes free radicals.