Lewis has the collection of minerals shown in the picture below. He knows that a harder mineral will scratch a softer mineral. He wants to design an experiment that will answer the following question:

Which of the minerals in the collection have a greater hardness than a rock made of marble?

Which of these is a fair test that he could do to answer the question?
A.
Separate the minerals into light and dark colors, and then try to scratch the marble with the light colored minerals.
B.
Separate the minerals into ones that feel heavier and lighter, and then try to scratch the marble with the heavy minerals.
C.
Try to scratch the marble with each of the minerals, and group the minerals that do scratch the marble together.
D.
Try to scratch the pink quartz with each of the minerals, and group the minerals that do not scratch the pink quartz together.