单项选择题

Yesterday was Jim’s birthday. He got many presents from his friends and family. All the gifts were wrapped in colored paper. Some of the packages were large while others were very small. Some were heavy, and others were light. There was one blue package which had a book in it. Another one was long and narrow—it had an umbrella in it. Jim’s sister gave him a big, round package. He thought it was a ball, but it was not. When he removed the yellow paper that covered it, he saw that it was a globe of the world.
After that, his brother gave him another present. It was a big box wrapped in green paper. Jim opened it and found another box covered with red paper. He removed the paper and saw a third box, this one was blue in color. Everyone laughed as Jim opened the boxes. There were six of them! In the last one he found a small white envelope. There was a piece of paper in the envelope which said: "Go to the big bedroom. Look in the closet near the window. You will see three suitcases: a black one, a brown one and a gray one. Your birthday present is in one of these suitcases."
Jim went to the large bedroom. He went to the closet and opened the suitcases. He had to open all of them before he saw his brother’s present. He was very happy. It was just what Jim wanted—a computer.
As Jim opened the boxes people laughed because ______.