$7-$ For the flow net shown, the

head difference is $5\mathrm{.}0m$ and $k=$

$4{10}^{-6}\frac{m}{s}$ The pressure head

at point $3$ is

a$)3\mathrm{.}6m$

b$)1\mathrm{.}5m$

c$)2\mathrm{.}9m$

d$)1\mathrm{.}4m$