An office supply store will begin stocking a new type of pen. Expected monthly demand is $800$ units. The store is open $300$ days a year. The supplier price schedule per pen is as follows: less than $200,$ $$4\mathrm{.}0$; greater or equal to $200$ and less than $400,$ $$3\mathrm{.}8$; and greater or equal to $400,$ $$3\mathrm{.}6.$ Ordering cost is $$40$ and annual holding cost is $$6$ per pen. Round your answers to zero decimal digits. The optimal order quantity for the pen is:

$300$

$100$

$400$

$200$