Parabolas like [tex] y=ax^2 [/tex] have the y-axis as their symmetry axis, so options B and D are surely wrong.
Moreover, parabolas like [tex] x=ay^2 [/tex] have the x-axis as their symmetry axis. If [tex] a>0 [/tex] the parabola is concave rightwards, if [tex] a<0 [/tex] the parabola is concave leftwards.
Since your parabola is concave leftwards, the only feasible option is [tex] x=-2y^2 [/tex]
