Pressure at (1)

$P_1=P_{atm}+\rho g (2h)$

Applying Bernonli's Theorem between two point (1) and (2)

$P_{atm}+2 \rho gh+\rho g (2h)+\large\frac{1}{2}$$ 2 \rho v^2$

$\qquad= P_{atm}+(2 \rho)g (0)+\large\frac{1}{2} $$2 \rho v^2$

Solving we get,

$v= 2 \sqrt {gh}$

Hence b is the correct answer