Which of the following parametric equation doesnot represent a parabola

x=aT2,y=2aT represents a parabola.in(a) a=1,T=t+1, in (b) a=a,T=(t−1)in(c) a=3,T=sin⁡t. But in (d)if 2aT=2acos⁡t⇒ T=cos⁡t which does not satisfy x=aT2