A、Four. B、Five. C、Six. D、Seven. CHow many people are mentioned in the passage?

Peter wondered why he didn’t have many friends. The reason was he was always taking, never giving.
    One day Peter told Bill, "I’d like to give a party on Saturday. I’d like you to come and bring Martha, too."
    "Thanks, Peter. We would be happy to come."
    "Perhaps you would like to bring your violin. You and Martha sing well together. I’m sure everyone will want you to sing for us."
    That was how Peter began to plan his party. Next he asked another friend, Betty, to bring a cake. "You make the best cake in the world, Betty, and I prefer to eat your cake than have one from the bakery."
    Peter invited several other friends to come to his party. He did not forget to ask something from each of them. He even asked Jim and Mary Jackson to let him give the party at their house. They agreed.
    The party was a big success. However, as the guests were leaving they said "thank you" to Bill and Martha for music, Betty for the cake, the Jacksons for the use of the house and to others for their hard work. To Peter they simply said, "Thanks for the invitation."