Assume the heights in a female population are normally distributed with mean 65.7 inches and standard deviation 3.2 inches. Which of the following pairs of heights most closely divides the population into three groups, where 25% are in the shortest group, 25% are in the tallest group, and 50% are in between?

a. 5 feet 4.3 inches, 5 feet 7.1 inches

b. 5 feet 4.0 inches, 5 feet 7.4 inches

c. 5 feet 3.0 inches, 5 feet 8.4 inches

d. 5 feet 3.5 inches, 5 feet 7.9 inches