A client, now 37 weeks pregnant, calls the clinic because she’s concerned about being short of breath and is unable to sleep unless she places three pillows under her head. After listening to her concerns, the nurse should take which action（）

A. Make an appointment because the client needs to be evaluated.

B. Explain that these are expected problems for the latter stages of pregnancy.

C. Arrange for the client to be admitted to the birth center for delivery.

D. Tell the client to go to the hospital; she may be experiencing signs of heart failure from a 45% to 50% increase in blood volume.

在数据库的三级模式体系结构中，外模式与模式之间的映象(外模式/模式)，实现了数据库的 【10】 独立性。