Could you briefly explain?

Suppose you computed a mean from a sample "A" with n_A=100 observations of mu_A=6 along with a sample standard deviation of std_A = 1. Suppose you further compute and a mean from another sample "B" with n_B=50 observations of mu_B=5 along with a sample standard deviation of std_B=1.5. What is the 90% confidence interval for the difference in means, d=mu_A-mu_B? Assume the sample size is sufficiently large to assume an N(0,1) distribution for whatever underlying test statistics you use to compute your confidence interval. O [0.540, 1.461] O [0.608,1.392] [0.612, 1.388] O 0.670, 1.330