Your computer's IP address is $201\mathrm{.}18\mathrm{.}149\mathrm{.}37/28.$ Which one of the following is a valid default gateway for this address?

a$.$

$201\mathrm{.}18\mathrm{.}149\mathrm{.}46$

b$.$

$201\mathrm{.}18\mathrm{.}149\mathrm{.}17$

c$.$

$201\mathrm{.}18\mathrm{.}149\mathrm{.}32$

d$.$

$201\mathrm{.}18\mathrm{.}149\mathrm{.}48$