Gus's Gourmet Burger Shop is open from $11$ a$.$m$.$ to $7$:$00$ p$.$m$.$ daily. If Gus's sells an average of $540$ burgers per day using $3$ cooks each working $4$ hours per day, what is the single factor produttivity of this restaurant in terms of cooks' labor hours?

$36$ burgers per labor hour

$9$ burgers per labor hour

$45$ burgers per labor hour

$67\mathrm{.}5$ burgers per hour