Which sentence best describes how art in Buddhist cave temples along the Silk Road reflects the beliefs of the Chinese people?

___ A. The cave temples were built to be sheltering places for revered emperors when they traveled from town to town.
___ B. The cave temples served as houses for the crews who built the Great Wall of China.
___ C. The cave temples were built to store silk and porcelain, which the Chinese valued above all other goods.
___ D. The cave temples were built as religious shrines and retreats for travelers and monks.