The crime described in this scenario is known as "C. Data diddling." Data diddling refers to the unauthorized alteration or manipulation of data for personal gain or to deceive others. In this case, the timekeeping clerk manipulated the overtime data by filling out forms with the names of employees who frequently worked overtime, but entered his own employee number, resulting in him receiving extra pay for overtime he did not actually work. This action involves fraudulent manipulation of data for personal financial benefit.