The first person to discover that atoms were made up of individual "parts" while working on phosphorescent substances was marie curie j. j. thompson henri becquerel enrico fermi

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.