Why is that cable sticking out of your ear?

You have recently run a 50 meter network connection across the building, and now you’d like to make sure that the punchdowns and crimps have connected the correct pins on each side. Which of these tools would be the best way to confirm your wiring map?

A) Multimeter

B) Loopback plug

C) Cable tester

D) Null-modem plug

E) Have one person yell while you listen on the other side