Final answer:
Exfoliation is the process that occurs when layers of rock are stripped away due to the reduction of pressure and is often associated with jointing. Jointing refers to the natural cracks or joints that can expand and lead to exfoliation when the rock is unloaded.
Step-by-step explanation:
Exfoliation is probably the result of unloading and jointing.
Exfoliation is a geological process where layers of rock are peeled away from the Earth's surface due to the reduction in pressure when overlying rock material is removed by erosion or other processes. This unloading leads to expansion and fracturing, often along existing joints in the rock, which is why option A) jointing is the correct fill-in-the-blank completion for this statement.
The photograph from Enchanted Rock State Natural Area in Texas is an example of sheet exfoliation on a granite dome, illustrating the effects of unloading and jointing on rock formations.