In a population, how do alleles at a microsatellite locus differ from each other?.

answer; i believe that the correct answer is ; males are hemizygous for the x chromosome;

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.