A biologist wants to know which fertilizer will result in the tallest pea plants. A chemist wants to know how much energy is required to change liquid water into water vapor. A geologist wants to know which type of soil is most permeable to water. A physicist wants to know what type of material reflects the most light.

Which of the following methods can best be used by all of these different scientists to answer their individual questions?
A.
taking a survey of their fellow researchers
B.
drawing a diagram as a model
C.
using popular magazines as reference materials
D.
performing a controlled experiment