Two major automobile manufacturers have produced compact cars with the same size engines. We are interested in determining whether or not there is a significant difference in the MPG (miles per gallon) of the two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The MPG for each manufacturer and driver is shown below.

Driver	Manufacturer A	Manufacturer B
1	31	25
2	26	19
3	25	24
4	25	21
5	24	21
6	28	22
7	30	25
8	24	24

The value of the test statistic is _____.

a. 2.365

b. 1.96

c. 4.221

d. 4.513