A researcher finds that white bread contains more preservatives and has a higher moisture content than wheat bread. She designs a test to determine whether the type of bread, white or wheat, affects the amount of mold growth. What must be done for the researcher to accurately measure the dependent variable?

A. She will need to allow mold to grow for more days on the white bread, since it contains more preservatives, to measure the dependent variable.
B. She will need to limit the dependent variable to white bread or wheat bread.
C. She will need to allow mold to grow for fewer days on the white bread, since it contains more preservatives, to measure the dependent variable.
D. She will need to learn out how to quantitatively measure mold growth to measure the dependent variable.

(I put 99 points on this; and you'll receive brainliest).