Paul and I live in the same building. His room is on the sixth floor but mine is on the fifth. He's very careless and sometimes he gets into trouble. Last Friday afternoon the young man and his friends went to spend the weekend on a wild island. They could swim, fish, play the guitar and sleep in the quiet place at night. They enjoyed themselves there. On the third morning they decided to get back to the land. But their boat hit a rock and soon went down. With the villager's help, they swam to the bank. Luckily none of them was hurt. They took a taxi and half an hour later they arrived at our town, but it was two in the night. The young man was hungry and thirsty. He wished to get home as soon as possible. Something was wrong with the lift, so he had to go up the stairs. He stopped by my door and brought out a key. Of course he could not open the door. Half an hour passed but he failed. He became angry and shouted, "I'll cut you down with a knife!" The noise woke me up and I opened the door. I understood at once what was happening and said, "You're trying to open a wrong door, Paul!" "Sorry, I can't agree with you, Charlie!" said the young man, "It's my room. You've entered it by mistake!" Paul couldn't open the door because   _  .
it wasn't his room he couldn't find the right key he didn't find the keyhole he was too hungry to do it