If \[f(x)=\left\{ \begin{align} & a{{x}^{2}}+b;\,\,x\le 0 \\ & \,\,\,\,\,\,\,\,\,{{x}^{2}};x>0\, \\ \end{align} \right.\] possesses derivative at \[x=0\], then

• A.            \[a=0,b=0\]                               
• B.            \[a>0,=0\]
• C.            \[a\in R,=0\]
• D.            None of these