5. Which of the following statements about a con- trolled experiment is true?
a. All the variables must be kept the same.
b. Only one variable is tested at a time.
c. Everything can be studied by setting up a con-
trolled experiment.
d. Controlled experiments cannot be performed
on living things.

option a and d is the correct answer

i hope this u

plz mark as the brainliest answer

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.

in addition to spreading humanist ideas, erasmus has contributed to criticism of corruption in the church.