Which one of the following polynomial functions has range equal to all real numbers?

MATHEMATICS · Single correct · AP · AP Precalculus · Polynomial and Rational Functions · Polynomial and Rational Functions

Problem

Which one of the following polynomial functions has range equal to all real numbers? (a)

q(x)=-x^4+7

(b)

r(x)=4x^3-5x

(c)

t(x)=x^4-6x^2+5

(d)

u(x)=x^6-x^2