Choice "A" is correct. A flexible budget adjusts the budget amounts for different levels of activity. The flexible budget identifies volume components of variances from planned activity.Choice "c" is incorrect. The primary feature of flexible budgets is their ability to adjust to actual volume based upon established relationships between revenue and variable costs. They are not simply flexible in the sense that amounts or selected line items can be adjusted or modified during the budget period.Choice "d" is incorrect. The flexible budget isolates the impact of changes in volume on sales and variable costs, not variable costs only.Choice "b" is incorrect. Although a flexible budget can be used for several products or divisions, their primary feature is the adjustment of those budgets for different activity levels.