What do scientists hope to learn from studying DNA extracted from tortoiseshell fossils?

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.

its probably to later but whats the question

if you listed your answers right then i believe your answer is b.