First, let's solve for x in the inequality to find an interval, the options that are not included in the interval are not part of the solution set, we can do it by following these steps:
1. 3x-18> 12 , add 18 on both sides:
3x - 18 + 18 > 12 + 18
3x > 30
2. Divide both sides by 3:
3x/3 > 30/3
x > 10
So, to be a part of the solution, x must be greater than 10, then the interval that represents the solution is (10, ∞). From the given options, the only one that is not included in this interval is 8, because it is less than 10, then the answer is 8.