Answer: "My dog (which is a poodle) is almost twelve years old.
Explanation: A nonrestrictive clause is a dependent clause, that is to say a clause that cannot stand alone as a sentence. Moreover, a nonrestrictive clause does not contain essential information for a sentence, but rather additional information. In that way, if this type of clause is eliminated from a sentence, the meaning of the sentence does not change. Nonrestrictive clauses are usually found between commas or parentheses. In the sentence "My dog (which is a poodle) is almost twelve years old", "(which is a poodle)" is a nonrestrictive element because it does not add essential information to the sentence. Moreover, this clause is found between parentheses and it has been introduced by the relative pronoun "which", which is generally used to introduce dependent clauses.
