Final answer:
Option (c) 'confused by the sign, the driver made the wrong turn' correctly transforms the italicized clause into a past participial phrase that acts as an adjective, directly describing the driver.
Step-by-step explanation:
The student's question asks which sentence correctly turns an italicized clause into a past participial phrase. To determine if a sentence is written in passive voice, we look for a subject that is not conducting the action but is being acted upon, a form of the verb "be" with a past participle, and the potential addition of a prepositional phrase starting with "by." In the context of participial phrases, they often start with a verb in its past participle form and usually describe a noun, serving as adjectives. In the provided sentences, option (c) confused by the sign, the driver made the wrong turn correctly converts the clause into a past participial phrase by removing the form of "be" and creating a modifying adjective phrase that directly describes the driver.