The variables x, y, and z represent polynomials where x = a, y = 3a – 5, and z = a2 + 2. what is x2y – z in simplest form?
a. 2a2 – 5a – 2
b. 3a3 – 6a2 – 2
c. –3a3 – 2
d. –3a2 – 2