Two Independent Samples of Sizes 25 and 35 Are Randomly

Multiple Choice

Two independent samples of sizes 25 and 35 are randomly selected from two normal populations with equal variances (assumed to be unknown) .In order to test the difference between the population means,the test statistic is:

A) a standard normal random variable.
B) approximately standard normal random variable.
C) Student t-distributed with 58 degrees of freedom.
D) Student t-distributed with 33 degrees of freedom.