What is this phrase?
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Answer:
B: Appositive Phrase
Explanation:
Appositives are nouns or noun phrases that follow or come before a noun giving more information about it (noun).
In this example the appositive phrase "famous actress" follows Susan Sarandon and gives more information about it (Susan - a noun).
Another example could be like this,
William Wordsworth, a romantic poet, had remained Poet Laureate of the United Kingdom from 1843 to 1850.