The noun phrase in English can reach high levels of complexity through various layers of pre-modification and post-modification. Based on the rules for noun phrase expansion and the use of appositives, choose the CORRECT alternative.
"Dr. Smith, the renowned cardiac surgeon, presented his findings" contains a restrictive relative clause that limits the reference of the subject.
"Dr. Smith, the renowned cardiac surgeon, presented his findings" contains an adjective phrase that functions as a predicator in the sentence.
"Dr. Smith, the renowned cardiac surgeon, presented his findings" contains a non-restrictive appositive that clarifies the identity of the head.
"Dr. Smith, the renowned cardiac surgeon, presented his findings" contains a prepositional phrase acting as the primary head of the construction.