If the Sampling Distribution of Cannot Be Assumed Normal,we

If the sampling distribution of cannot be assumed normal,we _________ .

A) are unable to compute a confidence interval
B) are still able to use the z distribution to compute a confidence interval
C) must use the t_df distribution with n₁ + n₂ - 2 degrees of freedom to compute a confidence interval
D) must use the t_df distribution and calculate the degrees of freedom using n₁,n₂,s₁,ands₂ to compute a confidence interval