$1.$ An $8-$m simply supported beam is carrying an ultimate uniform load of $84\mathrm{.}6$ kN$/$m$.$ The beam cross section is $400$mm wide by $820$ mm deep. It is reinforced for tension with $4$ nos. of $20$ mm diameter rebars with $2$ vertical legs of $10$ mm diameter shear reinforcement. The concrete cover up to the centroid of the tension reinforcement is $70$ mm$.$ If f$$c $=21$ MPa, and fy $=420$ Mpa, calculate for the ultimate shear force that must be resisted by the beam, in kN$.$

a$.270$

b$.272\mathrm{.}2$

c$.285$

d$.275$