Which of the following is true of red blood cells? A. They live for only 120 days. B. They have multiple Nuclei. C. They live for only about 20 days. D. Once created in bone marrow, they circulate for our lifetime.

A. They live for only 120 days is correct. They are created in the bone marrow and destroyed in the spleen "red blood cells graveyard"

B. They have multiple Nuclei. Red blood cells don't have a nucleus but some can present structures called Jolly's bodies that are small pieces of the nucleus that they lost in the differentiation process

C. They only live for only about 20 days. No, red blood cells live for about 120 days

D. Once created in bone marrow, they circulate for our lifetime. Again, they have a limited lifetime

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.