An Industrial Designer Wants to Determine If the New Design

An industrial designer wants to determine if the new design for a piece of office equipment will result in fewer errors.The designer sets up a machine with the old design in one room,and a machine with the new design in a second room.He counts how many errors are made using each of the two machines.In this study,what do you call the number of errors made

A)  extraneous variable 
B)  dependent variable 
C)  independent variable 
D)  control variable