Let p(x)=2x4−x2+3 and q(x)=x3−4x. Define r(x)=p(x)−q(x). Which of the following correctly describes r(x)?
a) degree 4, positive leading coefficient, even
b) degree 4, positive leading coefficient, neither even nor odd
c) degree 3, negative leading coefficient, odd
d) degree 4, negative leading coefficient, neither even nor odd