In constructing 95% confidence interval estimate for the difference between the means of two normally distributed populations, where the unknown population variances are assumed not to be equal, summary statistics computed from two independent samples are as follows: n1=50x1 b bar =756s1=35 n2=50x2 _bar=762 s2=30 The upper confidence limit is: A. 6.78 B. 77.3 C. 18.78 D. 89.3