4. what is used to make a linkage map for a group of organisms?
a the number of different genes found in the group
o b the number of phenotypes a gene set can produce in the group
c the number of traits one gene set can control in the group
d the number of times linked genes are separated in the group

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.

age range would be the answer