Final answer:
The percentage of newborns infected with varicella in the last 4 weeks of pregnancy is at risk of both clinical varicella and a higher mortality rate.
Step-by-step explanation:
The correct answer to the question is d. All of the above. In the last 4 weeks of pregnancy, the percentage of newborns who are infected with varicella (chickenpox) is at an increased risk of serious complications. This includes clinical varicella, where the baby develops visible symptoms of the infection, as well as a higher mortality rate.