$12\mathrm{.}66$ A rectangular sluice gate, $122$ cm wide and $183$ cm deep, hangs in a vertical plane. It is hinged along the top $(122$ cm $)$ edge. If there are $6\mathrm{.}4$ meters of water above the top of the gate, what horizontal force applicd at the bottom of the gate will be necessary to open it$?$ Refer to Exhibit $12\mathrm{.}66.$

a$.,75kN$

b$.83$ kN

c$.92$ kN

d$.98$ kN

Exhibit $12\mathrm{.}66$