Assume a network with the CIDR network address $137\mathrm{.}48\mathrm{.}0\mathrm{.}0/20.$ Also, assume the network is partitioned into $4$ subnetworks. How many hosts are available to each subnetwork?

$\_\_\_2^9$

$\_\_\_2^10$

$\_\_\_2^11$

$\_\_\_2^12$