Final answer:
The expression 3(a-b) stands for three times the difference of two integers, not the square of that difference or any other option provided.
Step-by-step explanation:
The expression 3(a-b) represents three times the difference between two integers a and b. It does not represent squaring their difference, nor does it indicate their squares being subtracted, or any operation involving six times their difference. The operation of squaring an integer is denoted by raising it to the power of 2. If we had (a - b)², this would be the square of their difference, but 3(a-b) is simply the difference, a - b, multiplied by 3.