The legacy program for listing files in the printer queues from the command line is:

A.
lpd

B.
lpr

C.
lpstat

D.
lpq

Explanation/Reference:
From the man pages:
lpq  shows the current print queue status on the named printer. Jobs queued on the default destination will be shown if no printer or class is specified on the command-line.

A) does not exist
B) sends a file (or stdin) to the printer
C) prints cups status information