the highlighted part of the sentence is called an Professor Plum, who had been to the mansion before, expertly navigated the maze of rooms and corridors to quickly reach the conservatory.

Question

Vocaloid · Answer

Answer choices:
 a.prepositional phrase.
b.appostive.
c.conjunctive adverb.
d.indirect object

Highlighted phrase is: who had been to the mansion before

Vocaloid · Answer

Notice how the highlighted phrase is separated by commas and gives more information about the preceding noun. What do we call such a phrase?