$.$ Water flows on a $5\mathrm{.}4$m wide open channel at a depth of $1\mathrm{.}20$m$.$ The channel bed is on a slope of $0\mathrm{.}001.$ Roughness coefficient is $0\mathrm{.}025.$ Compute the discharge through the channel in m$3/$s$.$

a$.8\mathrm{.}69$

b$.7\mathrm{.}24$

c$.6\mathrm{.}25$

d$.5\mathrm{.}32$