Consider a packaging facility that packages some product delivered to the facility by trucks.

Every day, trucks arrive evenly from $8$am to $4$pm and unload $40$ units of unpackaged produet

per hour at a small warehouse attached to the packaging facility. The assembly process takes

unpackaged items from the warehouse and spends $3$ minutes to package each item. The

packaged items are shipped out immediately to retail stores. The warehouse can hold up to $120$

units of the product. Once the warehouse is full, the trucks have to hold the items and wait its

turn to unload items it carries. The facility continues to run until all the items delivered in a day

are all packaged.

According to the above information, what is the maximum number of items that are waiting on

the trucks at any given time?

O $120$

O $100$

O $40$

O $160$