The following statements have been made regarding different types of budget:
(i) A flexible budget can be used to control operational efficiency.
(ii) Incremental budgeting can be defined as a system of budgetary planning and control that measures the additional costs that are incurred when there are unplanned extra units of activity.
(iii) Rolling budgets review and, if necessary, revise the budget for the next quarter to ensure that budgets remain relevant for the remainder of the accounting period.
Which of the above statement(s) are true?