Please help meee how to do this
Please

the correct answer: the index of refraction of the second medium is lower i tried this persons answer and it was wrong this person is lying

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.

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: