What main substance would an influenza vaccine contain

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.

some of your causes might be acidic rain or natural wildfires that cause the parks to be degraded

hope this any more questions i am here plz mark brainliest

human-caused climate hope this

digestion

it excretes wastes