An adverse labour efficiency variance means that employees are taking too long to produce the products. Employing more highly skilled labour should help to speed up the process so statement (i) is applicable. Supervision of employees may help to improve efficiency standards by ensuring less time is wasted by employees. So statement (ii) is applicable. Asking employees to work paid overtime will not help to improve the efficiency because it is unlikely to reduce the number of hours worked. Employees may even slow down further and become more inefficient if they think that they can work overtime and be paid extra wages. So statement (iii) is not applicable.