Foods that are high in fiber (like whole grains) usually contain both soluble and insoluble fiber. Insoluble fiber contributes primarily to gastrointestinal health. If half of the fiber in the oatmeal is soluble and the other half is insoluble, how many grams of insoluble fiber are in the oatmeal?

a) 2g
b) 3g
c) 4g
d) 5g