C. His life before the change and how unhappy and unappreciated he
was
Explanation:
Gregor found out his true worth after he turned into a bug. He realised that he was only appreciated when he was still a man because of what people around him, his family and employer can get from him. When he became a bug he realised how unappreciated he was since he couldn't do anything useful for them anymore. HE HAD BECOME WORTHLESS
The sentence that contains an error is: Marcus and Jason will been playing in a soccer tournament all weekend. This sentence contains an error because of the word "been". The word "been" is incorrectly used in the sentence. The correct would should be "be".