it is a, the zero property. It is so since you are multiplying zero to get an answer of zero.
I will try to elaborate.
The "Zero Product Property" says that:
If a × b = 0 then a = 0 or b = 0
(or both a=0 and b=0)
18 x 0 = 0
Let's say that 18 = a and 0 = b. By the converse of the statement, it states that if a or b is zero, then it must be the zero property. Since b is in fact, zero, then we can conclude that it is, in fact, the zero property.
