A、She will clap. B、She will blink. C、She will smile. D、She will imitate her mother. C短文明确提到了当母亲做婴儿喜欢的事时，婴儿就会微笑，故C为答案。

Some people thought babies were not able to learn things until they were five or six months old. Yet doctors in the United States say babies begin learning on their first day of life. The Eunice Kennedy Shriver National Institute of Child Health and Human Development is a federal government agency. Its goal is to identify which experiences can influence healthy development in people. Research scientists at the Institute note that babies are strongly influenced by their environment. They say a baby will smile if her mother does something the baby likes. A baby learns to get the best care possible by smiling to please her mother or other caregiver. This is how babies learn to connect and communicate with other people. The American researchers say this ability to learn exists in a baby even before birth. They say newborn babies can recognize and understand sounds they heard while they were still developing inside their mothers. A study from the Netherlands found evidence that unborn babies can remember sounds. Dutch researchers studied almost one hundred pregnant women. They played sounds to the growing unborn babies and watched their movements. They found that by thirty weeks of development the unborn babies could remember a sound for ten minutes. By the thirty-fourth week, they could remember the sound for four weeks.
16 What do the American doctors say about babies?
17 What is the purpose of the National Institute of Child Health and Human Development?
18 What will a baby do if her mother does something she likes?
19 According to the speaker, what did the Dutch researchers find out?