A sociologist is studying the effect of having children within the first three years of marriage on the divorce rate. From city marriage records she selects a random sample of 400 couples that were married between 1985 and 1990 for the first time, with both members of the couple between the ages of 20 and 25. Of the 400 couples, 220 had at least one child within the first three years of marriage. Of the couples that had children, 83 were divorced within five years, while in the couples that didn't have children only 52 were divorced within three years. Suppose p1 is the proportion of couples married in this time frame that had a child within the first three years and were divorced within five years and p2 is the proportion of couples married in this time frame that did not have a child within the first two years and were divorced within five years.
Referring to the information above, the estimate of p1 - p2 is
a. 0.3100
b. 0.0884
c. 0.3773
d. 0.3375