Planet earth Brittle deformation:

A. produces folds, like anticlines.
B. is more likely to occur deep in the crust than at the surface.
C. occurs when many atomic bonds are broken quickly and rock pieces separate.
D. is favored by high-temperature, high-pressure conditions.

C. occurs when many atomic bonds are broken quickly and rock pieces separate.    

Explanation:

Planet earths Brittle deformation occurs when many atomic bonds are broken quickly and rock pieces separate.  

This brittle deformation occurs when rocks along active plate boundaries are subjected to physical stress such as change temperature which causes their atomic bonds to break and the rock becomes shattered, this is termed brittle deformation.

There is also ductile deformation in rocks