d
The initial velocity of the water stream is given as,

\(v=\sqrt{2 g(H-h)}\)

The time taken by stream to hit the surface is,

\(h=\frac{1}{2} g t^{2}\)

\(t=\sqrt{\frac{2 h}{g}}\)

The horizontal range can be calculated as,

Horizontal range \(=v t\)

\(=\sqrt{2 g(H-h)} \times \sqrt{\frac{2 h}{g}}\)

\(=2 \sqrt{(H-h) h}\)

\(=2 \sqrt{(1-0.25)(0.25)}\)

\(=0.866 m\)