A planar surface along which a mineral tends to break due to atomic weakness:

• A. Cleavage
• B. Bond
• C. Cleavage Plane
• D. Crystal

Answer: (C)

The plane along which a mineral tends to break is called the cleavage plane. Cleavage describes the mineral’s tendency to split along flat, planar surfaces that reflect weaker bonds in the crystal structure. The surface itself is that specific cleavage plane, a reproducible sheet where breakage tends to occur.

A bond is just a single connection between atoms, not a defined plane of breakage. A crystal refers to the entire, orderly arrangement of atoms, not to the particular surface where fracture happens. So the best term for describing that planar surface is the cleavage plane, which is why that option fits this description.