Which of the following was part of the ozone depletion problem?
mining waste
chlorofluorocarbons
ddt

Chlorofluorocarbon (CFC) is used as the aerosol propellant. An aerosol is a suspension in the gaseous form of solid or liquid particles. When these compounds reach the stratosphere, UV light affects them and they release chlorine atoms. Chlorine atoms are capable of breaking down ozone molecules. With fewer ozone molecules, the ozone layer becomes thinner and harmful UV light passes through it. 

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.

a researcher conducts an experiment on the secretion of a particular hormone in mice. scientists inject mice with a substance that stimulates the production of the hormone. the scientists then test the levels of hormones produced by the mice. the tool used to measure the hormones consistently detects the levels at 10 points lower than the actual hormone levels in the mice. this tool makes measurements, but the measurements aren't .

explanation:

no u