Which graph corresponds to an object moving with a constant negative acceleration and a positive velocity?

According to the question we get, 

let us take the acceleration to be a negative constant, 

a = -B

now we know  a = $\frac{dv}{dt}$

$\frac{dv}{dt}= -B$

$$\begin{gathered} \frac{dv}{dt}=\frac{dx}{dt}x\frac{dv}{dx} = - B \\ but \frac{dx}{dt}= v \\ now we get, v \frac{dv}{dx}=-B \\ rearraging the above we get, \\ vdv = -Bdx \\ no integrating both sides with 0 - v and limits of dis\tan ce 0 - x \\ {\int }_0^{v}vdv = {\int }_0^{x}dx \\ after integration we get {\left|\frac{v^2}{2}\right|}_0^v = -B{\left|x\right|}_0^x + C ( c is the cons\tan t ) \\ \frac{v^2}{2}=-Bx+c \\ x = \frac{-v^2}{2B}+\frac{c}{B} \end{gathered}$$