Read the following article and answer the question. Article: I met the old man at a cafe. "Did you hear the radio news yesterday?" he asked me. "No," I replied. "Anything exciting?""Exciting? NO! Something very sad. A group of hungry dogs killed and ate my best friend." "Oh, dear!" I cried. "How did it happen?""He was working on the hillside when the dogs attacked him. When he didn't return, I went to the hillside and found...""His body?" I asked. The old fellow drank half of his coffee. "No. I told you they were hungry dogs, didn't I? The big bones were lying every where. But they found this." He pushed open a match box he was holding in his hand. In it was a man's thumb, lying on some white bloody material. "This is my friend's right thumb. The dogs ate the rest of him". The old man began to cry. He finished his coffee quickly and left the cafe. I drank mine and called the waiter. "I'll pay the gentleman's bill. His poor friend--how terrible!""You've heard the news?" The waiter laughed. "Sure. There's a hole in the bottom of the match box. He put his own thumb through the hole. The blood is red ink, I believe. Is the story worth a cup of coffee, sir?""But he held the box in his right hand.""Yes, but listeners look into the box. They just can't take their sight off that terrible thing.""And when he tells the story, he gets free cup of coffee!" I said, laughing. "Yes, sir, but only from strangers who come to this town, and, of course, he does us no harm!" Question: The waiter hadn't let out the truth of the old man's story earlier because _ . Answer:

Choices:
a). he was nobody but the best friend of the old man.
b). the old man wouldn't pay for his coffee if he did.
c). the waiter hadn't seen through the old man's trick.
d). the old man helped the cafe in some way.
Answer:
d).