Marigold Corp. sells two types of computer hard drives. The sales mix is $30\%($Q$-$Drive$)$ and $70\%($Q$-$Drive Plus$)$ based upon quantity c units sold. Q$-$Drive has a unit variable cost of $$110$ and a selling price of $$160.$ Q$-$Drive Plus has a unit variable cost of $$150$ and a unit selling price of $$230.$ Marigold's fixed costs are $$1012500.$ How many units of Q$-$Drive would be sold at the break$-$even point?

$6131$

$14261$

$9983$

$4278$