Answer:
D. temperature
Step-by-step explanation:
Temperature is the main factor that brings about mechanical weathering. Mechanical weathering is the natural and physical breaking down of rocks from big ones to little ones. There are many examples of mechanical weathering and the common factor is temperature:
Frost Wedging - water expands as it freezes to ice increasing any crevices in a rock as it happens over and over, weakening the road
Thermal Expansion and Contraction - due to high day temperatures and low night temperatures. This causes cracks as stress, from temperature swings, is released.