First, the factor pairs for 18 are:
1, 18
2, 9
3, 6
Since the middle term is -3, the two factors must be 3 apart. The only pair that is 3 values apart is 3, 6.
Since the middle value is negative, the larger number is negative. This means that the 6 is negative.
z = -6
z = 3
Set each equal to 0;
z = -6
z + 6 = 0
z = 3
z - 3 =0
So your factors are (z+6) and (z-3), or answer B.
