CO2+H2O x to H2CO3 equals

the answer is otpion c) understanding

he wants to be heard one more time. he wants to be understood. he needs the truth one more time.

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.