Mr. and Mrs. Green had different ideas about where to go last weekend. Mrs Green wanted to go to Florida  to see her sister, but Mr Green didn't like to go there. He wanted to go to Maine . "Florida is too hot in summer," Mr Green said to Mrs Green. "Maine is quite cold," said Mrs Green, "I like swimming, but the water in Maine is usually not warm enough." "Florida is too far," said Mr Green, "We don't have enouh time to drive there. It'll take us more than two days." Just then, the telephone rang. Mr Green answered the phone. It was his mother. "Is that Jim speaking? Please cme quickly. I need help. I'm calling from the hospital in Boston." She said. They stopped the discussion , and they left for Boston at once. Who called them when they were talking?
Mr Green. Mr Green's wife. Mr Green's mother Mr Green's son