We want to write the product of z and x-y as a mathematical expression. To do this, we should think about what each phrase is telling us. The product of means that we are multiplying. The factors being multiplied are z and x-y. In this exercise, x-y is considered a single factor of the product, so we need to write it in parentheses.
& The product of z and (x-y)
& z * (x-y)
When we have a multiplication involving parentheses, we do not need to include any kind of multiplication symbol. Knowing that, let's simplify the obtained expression a bit more.
z * (x-y) ⇔ z(x-y)
This corresponds to option A.
