Suppose That X Is a Normally Distributed Variable on Each

Suppose that x is a normally distributed variable on each of two populations. Independent samples of sizes n₁ and n₂, respectively, are selected from the two populations. The mean of all possible
Differences between the two sample means is equal to which of the following?

A) The sum of the two sample means
B) The difference between the two sample means
C) The sum of the two population means
D) The difference between the two population means