Answer:
Option A: Their eyes searching the fog
Explanation:
An absolute phrase is one that modifies a noun in a sentence, not being connected to it by a conjunction. It is set off with a comma, and this part of the sentence can be removed from it without changing its meaning. Often, this kind of phrase contain a participial, but it is not mandatory.
Example:
Her body moving fast, Aby awed everyone with her natural dancing ability.