Every time you connect to the Internet, your computer is assigned a unique identification number that looks something like this: $123\mathrm{.}45\mathrm{.}245\mathrm{.}91.$ What is that ID number known as$?$

$($A$)$ Password

$($B$)$

Internet Protocol $($IP$)$ address

$($C$)$

Router $($RN$)$ number

Transmission $($TC$)$ code