Which of the following is not a pyrimidine?
guanine
cytosine
thymine
none of the above

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.

producers: apple trees, potatoes, carrots, grains, acorns, cabbage, grass, corn, lettuce

consumers: deer, mice, rabbits, chickens, squirrels, horses, worms, cows

predators: eagles, frogs, wolves, owls