Lamar has the following data:

Selling price $ $40$

Variable manufacturing cost $ $22$

Fixed manufacturing cost $ $177,000$ per month

Variable selling & administrative costs $ $6$

Fixed selling & administrative costs $ $147,000$ per month

If Lamar produces and sells $57,000$ units, what is the margin of safety in units?

Multiple Choice

$17,000$ units

$12,833$ units

$19,500$ units

$30,000$ units