Foods that are high in dietary fiber $($like whole grains$)$ usually contain both soluble and insoluble fiber. According to the Spreadsheet Report, there are $2\mathrm{.}3$ grams of soluble fiber $($Fib$-$S$)$ and $1\mathrm{.}6$ grams of insoluble fiber $($Fib$-$l$)$ in the oatmeal. What is the primary benefit of the insoluble fiber in oatmeal?

a$.$ Promotes bowel regularity

b$.$ Slows glucose absorption

c$.$ Prevents oxidative damage

d$.$ Reduces cholesterol absorption