A、At the back of the plane. B、Somewhere behind the pilot’s cabin in the front of the plane. C、On the fight-hand side of the plan

The air hostess was in the small kitchen at the back of the aero-plane preparing the trays for lunch when a little and lady came and spoke to her. "Could you please tell me," she asked, "where is the ladies lavatory in this plane?"
    "Yes, madam," said the air hostess and smiled. "It is right at the other end of the plane—at the front."
    The little old lady went too far. She walked all the way to the front of the plane, opened the door in front of her, and saw the captain of the aero-plane and the other officers. They were all busy at their work and did not see her. She went out again, shut the door and returned to the air hostess.
    "Oh, didn’t you find it, madam?" the girl asked her.
    "Yes, I did," said the little old lady. "But there are four men in the ladies lavatory watching television."