A client at 20 weeks gestation understands her baby's development when she states what?

The correct response is that at 20 weeks gestation, a fetus is typically around 7.5 inches long. This developmental milestone reflects the significant growth that occurs during the second trimester, where the fetus continues to develop its bodily systems and features. At this stage, major organs are functioning, and observable growth can be tracked in terms of length.

While other statements mention aspects of fetal development, they do not accurately represent typical milestones at 20 weeks. For example, breathing does not occur in the same way as it does after birth, as the fetus is still reliant on the placenta for oxygen. The ability to open the eyes and fully develop fingernails also occurs at later stages in gestation. Thus, the length of the fetus at 20 weeks is a key indicator of its development, making the statement about the baby's size the most accurate representation of a 20-week gestation.