In a drum$-$buffer$-$rope scheduling system, the "drum" represents which of the following?

A$)$ The drum is established after the constraint to protect the constraint from disruptions.

B$)$ The drum pulls production to the constraint for processing.

C$)$ The drum is the master schedule for the operation, which is focused around the pace of throughput as defined by the constraint.

D$)$ The drum acts as the constraint against too much being loaded into the master schedule.