c. The mist rolled over the trees in the mountains.
Explanation:
An allusion is an expression that refers to another person or thing without making a direct reference to it. In other words, allusion is talking about something without directly referring to it.
Among the given sentences, sentence c is an allusion. It alludes to or refers to the mist as "rolling over" the trees. While the other two sentences are similes with their use of "as" and "like" in making the comparisons.
