(d) Standard equation of projectile motion
$y = x\tan\theta - \frac{gx^{2}}{2u^{2}\cos^{2}\theta}$
Comparing with given equation
$A = \tan\theta$ and $B = \frac{g}{2u^{2}\cos^{2}\theta}$
So $\frac{A}{B} = \frac{\tan\theta \times 2u^{2}\cos^{2}\theta}{g} = 40$
[As $\theta = 45{^\circ},\ u = 20\ m/s,\ g = 10m/s^{2}$]