An ISP has $180\mathrm{.}18\mathrm{.}0\mathrm{.}0/16$ and we want to have $4$ subnets, then the new subnet mask will be:

Question $2$Select one:

a$.$

$255\mathrm{.}255\mathrm{.}192\mathrm{.}0$

b$.$

$255\mathrm{.}255\mathrm{.}128\mathrm{.}0$

c$.$

$255\mathrm{.}255\mathrm{.}0\mathrm{.}0$

d$.$

$255\mathrm{.}255\mathrm{.}255\mathrm{.}0$

e$.$

none