Which statement best explains the effect on membrane permeability of cholesterol and/or temperature?
a. adding cholesterol increases permeability because its steroid rings decrease the density of the hydrophobic membrane interior.
b. adding cholesterol reduces permeability because its steroid rings fill gaps in the hydrophobic membrane interior.
c. increasing temperature increases permeability because it increases the strength of hydrophobic interactions in the membrane interior.
d. adding cholesterol increases permeability because its steroid rings increase the density of the hydrophobic membrane interior.

B. adding cholesterol reduces permeability because its steroid rings fill gaps in the hydrophobic membrane interior

Explanation:

the core of the sun is so hot and there is so much pressure, nuclear fusion takes place, hydrogen is changed to helium. nuclear fusion creates heat and photons. when the heat reaches the earth it warms the molecules of the atmosphere, and they warm other molecules and so on.

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.