Question $2(2\mathrm{.}5$ points$)$

Marcello's gourmet salt operation has a maximum output of $500$ pounds$/$hr$.$ Marcello ensures product freshness by producing only on demand and never storing finished salt in inventory. The production starts at $9$ am and continues until all daily orders are completed. Given the orders of $1500$ pounds at $9am,300$ pounds at $1pm,$ and $500$ pounds at $3pm,$ at what time will the production for the day conclude?

$($a$)12pm$

$($b$)1pm$

$($c$)4pm$

$($d$)5pm$