which of the following is a travelling wave

Question

a) (x-vt)^2   b) (x+vt)^2   c) e^-(x-vt)^2  d) 1 / x+vt

Answer 1

I think , a function which can be expressed as a function of (x+vt) or (x-vt) represents a traveling wave.
Where v= velocity of wave, x = distance traveled in time t
So all functions given here are traveling wave