Final answer:
4. The organ systems are beginning to develop. During the first trimester, the baby's organ systems begin to develop and the reproductive organs differentiate. Fine hair called lanugo starts to grow on the face and fingers and toes are fully differentiated.
Step-by-step explanation:
The nurse should inform the client that during the first trimester of pregnancy, the baby's organ systems begin to develop. This includes the formation of the reproductive organs, such as the development of male or female sex organs. The nurse can also mention that fine hair called lanugo starts to grow on the baby's face and will eventually cover the body, and fingers and toes are fully differentiated. However, the nurse should not tell the client that the sex of the baby can be determined during the first trimester, as the differentiation of the sex organs typically occurs later, around weeks 9-12.