The Northern Co. manufactures office chairs. The following information is available for June: Selling price per chair $150 Variable cost per chair 90 Total fixed costs 99,000 If the company sells 1,500 chairs in the month of June, the margin of safety in units is _____. (Round-off the answer to the nearest whole number.)

a.-179 chairs b.-150 chairs c.-159 chairs d.-169 chairs