A scientist is researching how different types of grasses affect the rate of erosion on a hillside. The scientist builds a model of the hillside in his laboratory and conducts a controlled experiment that tests one variable—grass species. The scientist repeats the experiment three times. Each time, he gets different results. What should the scientist do next? A.
carefully analyze his experimental design to try to find an explanation for the conflicting results
B.
use statistics to modify his results so that all of the experiments end up supporting the same conclusion
C.
conclude that the species of grass growing on a hillside does not affect the rate of erosion
D.
stop studying erosion rates and find a new hypothesis to test