A manufacturer is considering dropping a product line. It currently produces a multi$-$purpose woodworking clamp in a simple manufacturing process that uses special equipment. Variable costs amount to $$6\mathrm{.}00$ per unit. Fixed overhead costs, exclusive of depreciation, have been allocated to this product at a rate of $$3\mathrm{.}50$ a unit and will continue whether or not production ceases. Depreciation on the special equipment amounts to $$20,000$ a year. Fixed costs are $$18,000.$ The clamp has a selling price of $$10$ a unit. Ignoring tax effects, the minimum number of units that would have to be sold in the current year to break even on a cash flow basis is

A$.$

$36,000$ units.

B$.$

$20,000$ units.

C$.$

$4,500$ units.

D$.$

$5,000$ units.