A particle moves along a parabolic path y=9 x^2 in such a way that the x component of velocity remains

a particle moves along a parabolic path y=9 x^2 in such a way that the x component of velocity remains constant and ha a value 1/3 m/s. the acccelaration of the particle is -
a)1/3 m/s along y axis
b)3 m/s along y axis
c)2/3 m/s along y axis
d)2 m/s along the y axis
Hint - answer is option D. how do you folks do it?
please help

x = constant speed * time = (1/3)t

Substituting for x in y=9 x^2 gives:
y = 9((1/3)t)²
= t²

y-velocity (v) = dy/dt = 2t

y-acceleration = dv/dt = 2

Answer d.