Under which condition would a body of rock be most likely to exhibit brittle behavior?

A body of rock would most likely exhibit brittle behavior under the condition of LOW TEMPERATURE.
At low temperature, the water in the crevices of the rock will freeze up, the freezing up of this water causes fractures in the rocks  and as time goes on the rocks become brittle and parts of it will start falling away.

The best way to tell its true color is to look at the minerals streak

Breacking the law and lazy