Which of the Following Gives the Best Description of What

Which of the following gives the best description of what the scientific method is?

A) It is the process of carefully following the steps of a lab procedure.
B) It is the guidelines that are followed during laboratory measurements.
C) It is unifying principle that explains a body of facts and relations.
D) It is the process of making observations and then designing ways to evaluate or explain those observations.
E) It is a guidebook for laboratory techniques that is followed by all chemists.