Blood flow through an arteriole when it dilates.
a) decreases
b) remains unchanged
c) increases

The correct answer will be option C - increases.

Explanation:

The dilation or vaso-dilation is the widening or increase in the diameter of the blood vessels- arteries, arteriole and veins.  

The vasodilation is caused by the relaxation of the smooth muscle which results in the increased flow of the blood through these vessels due to a decrease in the vascular resistance.

Thus, option C - increases are the correct answer.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.