Independent Simple Random Samples Are Taken to Test the Difference

Independent simple random samples are taken to test the difference between the means of two populations whose variances are not known, but are assumed to be equal. The sample sizes are n1 = 32 and n2 = 40. The correct distribution to use is the

A) t distribution with 73 degrees of freedom
B) t distribution with 72 degrees of freedom
C) t distribution with 71 degrees of freedom
D) t distribution with 70 degrees of freedom