Istanbul Industries Uses a Kanban System to Manage Production of the MI6

Multiple Choice

Istanbul Industries uses a kanban system to manage production of the MI6 subassembly. In an 8-hour day, they use 100 units per hour and use containers that can hold 23 units each. It takes 120 minutes to fill and move a container of parts to the right place on the MI6 line that is currently rated at a 15% safety factor.
-How many containers should the kanban system of Istanbul Industries be using?

A) 10
B) 15
C) 20
D) 25
E) 30