**Concept: The question tests on Arithmetic(Number Properties)**

**Solution:**

The best way to find out is by using the options. We will try to put values to satisfy the condition and see if we can get a - b as a negative integer.

Option A: |a - b| is positive.

If a = 2 and b = 4, |2 - 4| will be positive but 2 - 4 = -2

Option B: a/b is a positive integer.

If a = -2 and b = -1, a/b = 2 which be positive but -2 - (-1) = -2 + 1 = -1

Option C: (b – a) is a negative integer

a = -2 and b = -3, then b - a = -3 -(-2) = -1 and a - b = -2 - (-3) = 1

a = 2 and b = -3, then b - a = -3 -2 = -5 and a - b = 2 - (-3) = 5

a = 4 and b = 3, then b - a = 3 -4 = -1 and a - b = 4 - 3 = 1

So this is always True

Option D: (a + b) is a positive integer

a = 3 and b = 4, then a + b = 3 + 4 = 7 and a - b = 3 - 4 = -1

Option E: (ab) is a positive integer

a = 3 and b = 4, then a * b = 3 * 4 = 12 and a - b = 3 - 4 = -1

Option C