A psychologist has developed a set of activities which she hopes will help children develop better reading skills. In a study of the effectiveness of these activities, one class of second grade children learns with the activities. Another class of second grade children serves as the control, and learned without the activites. After some period of time, the reading skills of all of these children were assessed. A summary of these data is: n xbar s
Activities Class 21 51.48 11.01
No Activities Class 23 41.52 17.15

A 95% confidence interval for the difference in mean reading skill score between children that learned with activities and children that learned with activities and children that learned without activities is (use option 2, the conservative method for degrees of freedom):

a. 0.97 to 18.95 points
b. 2.53 to 17.39 points
c. 8.83 to 11.09 points
d. 6.45 to 13.47 points