ii and iii
polynomials are functions of quadratic,cubic,quartic etc involving only a non negative integer power of x.
since option (i) includes negative power(5x^-2) and option iv is a rational function
but option iii can be simplified to a polynomial function (x^2+(4x^3/2-1/2))=x^2+4x^2/2=x^2+4x
