"Oh, sorry," the old man says, "I didn't know you were her mother."

The person answers, "A girl, she is my daughter."

"You are wrong," the person says, "I'm her father."

Many boys and girls in western countries are wearing the same clothes. Many of them have long hair, so it is hard to tell whether they are boys or girls.

One day an old man is sitting on a chair near a pool. A person is beside him. The old man asks the person, "Is it a boy or a girl in the pool?"