If Employees Come in to Start Work Early, or Stay

If employees come in to start work early, or stay beyond scheduled hours, or come in to work on days off,

A) the extra time put in on the job could be used to re-classify those employees from non-exempt to exempt
B) the extra time put in on the job could qualify those employees for overtime pay
C) under the FLSA, they have volunteered their services for that extra time
D) the FLSA requires that they receive a raise