The sun, a star at the center of our solar system, is made mostly of hydrogen and helium.

which word or phrase is an appositive in the sentence?

1.)a star
2.)hydrogen and helium
3.)a star at the center of our solar system
4.)the sun

  A star at the center of our solar system.

Explanation:

  An appositive is a noun or a noun phrase that renames another noun right beside it. It can be short or long.

  On this case, the appositive is nonessential because its surrounded by commas, separated from the rest of the sentence. It interrupts the sentence.

  If the information given in the appositive is essential to the sentence´s meaning is called Appositive restrictive and commas are no longer used for these cases.

  I hope this answer helps you.

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