If organisms a, b, and c belong to the same class but to different orders and if organisms d, e, and f belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?

Any combination of D, E and F

Explanation:

Since A, B, and C belong to different orders, and D, E and F belong to the same order, the latter are more closely related and thus are expected to show a greater degree of structural homology. They are closer to their common ancestor than A, B and C.

answer; ////increased water pollution; ///////////////////////

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.