8). Consider taking random samples of size 100 from Population A with mean 85 and standard deviation of 15 and random samples of size 60 from Population B with mean 78 and standard deviation 12. a. Find the mean of the distribution of differences in sample means A) -7 B) 7 C) 78 D) 85 b. Find the standard error of the distribution of differences in sample means A) 0.35 B) 0.5916 C) 2.156 D) 4.65 c. How many degrees of freedom should be used when conducting inference with samples of this size? A) 99 B) 100 C) 59 D) 60