Answer:
Essentially taking someone else's work or ideas and saying that they are your own.
The correct answer is lonely because there is noone he can talk to unlike before. All his friends have been acting like strangers by not opening their doors for him when he needed someone to talk to. While feeling lonely, he felt expressing his thoughts to noone but himself.
In compound sentence, there are two independent clauses that are joined using a coordinator. While in complex sentence, there are two or more clauses with one essentially an independent clause while there can be on or more dependent clauses. The difference between compound and complex sentence is that there is no dependent clause in compound sentence and at least there is one dependent clause in complex sentence.
The 3rd one is your correct answer. :3
