Consider the following expressions:
(a) Polynomials: (i), (iii); Rational but not polynomial: (ii), (iv)
(b) Polynomials: (i); Rational but not polynomial: (ii), (iii), (iv)
(c) Polynomials: (i), (ii); Rational but not polynomial: (iii), (iv)
(d) Polynomials: (i), (ii), (iii); Rational but not polynomial: (iv)