Answer:
The most appropriate answer would be D-an experiment that reveals a new step in a metabolic pathway.
The discovery of a new step in the metabolic pathway would add on to the existing information.
It would help in better understanding of the process such as any disease or disorder related to the discovered step, enzymes used in the step, importance of the step et cetera.
Ultimately, it would help in developing new technology, process, or medicine related to the discovered step.