Is the underlined verb in the sentence transitive or intransitive? Will you please answer the telephone?

Verified Answer :

i'm  assuming that the underlined word is answer and i think its transitive. but i'm not completely sure.

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Which sentence uses an intransitive verb?                                                                  A.
I cheered after finishing the race.  
B.
My elderly neighbor knitted my sweater.                                                            
 C.
Mr. Phillips called the plumber for help.                                                                  D.
Zach used a box for a fort.