【单选题】

A、manufacturer has the following figure for the product

A、 OriginalData Increase VariableCost to ＄15 Unit selling 30 30 Unit variable cost 10 15 Fixed cost 3,000 3,000Budget selling units 300 300 Margin of safety is ______. (a)increase 50 units(b)increase 100 units (c)decrease 50 units (d)decrease 100 units