Given $y(0) =2000$ and $\large\frac{dy}{dx} =3200-20y^2$ then find the value of $\displaystyle\lim _{x \to \infty} y(n)$

Question

$(a)\;does\;not\;exist\\ (b)\;Given\;differential\;equation\; cannot\;have \;y(0)=zero \\ (c)\;-40 \\ (d)\;40$