Determine the smallest cross$-$sectional area A required for the members of the truss shown so that the horizontal deflection at joint $D$ does not exceed $10$ mm$.$

a$.305\mathrm{.}0m{m}^2$

b$.3050m{m}^2$

c$.30\mathrm{.}5m{m}^2$

d$.3\mathrm{.}05m{m}^2$