A study of injuries to in-line skaters used data from the National Electronic Injury Surveillance System, which collects data from a random sample of hospital emergency rooms. The researchers interviewed 161 people who came to emergency rooms with injuries from in-line skating. Wrist injuries (mostly fractures) were the most common. A plus four 95% confidence interval for the difference between the two population proportions of wrist injuries is?
A. 0.2909 ± 0.1674.
B. 0.2909 ± 0.1069.
C. 0.2909 ± 0.0907.
D. 0.2909 ± 0.1275