It is extremely useful for geologists, because most specimens of a given mineral are very close to the same hardness. ... So, we can conclude that not all the rocks are hard, and the hardness of rocks depends on how the atoms of the rock's minerals are bound to each other and how they are arranged.
Answer:
Rhodopsin is the photopigment in rods.
I believe the answer is B because carbon can easily form chains to bond together.
