FIELD sports store sells $1$ World Cup soccer ball for every $4$ regular style balls.

World CupRegularSoccer BallStyle BallSale price per ball$$20\mathrm{.}00$$$10\mathrm{.}00$Variable cost per ball$$10\mathrm{.}00$$$5\mathrm{.}00$

Total Fixed Cost for FIELD sports $$19,200.$ Assuming a constant sales mix. The break$-$even unit sales volume is:

Select one:

a$.$

$14,400$

b$.$

$6,144$

c$.$

$11,520$

d$.$

$3,200$