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.
-If the number of containers is reduced by 1, what would be the new required safety stock, all else being constant?

A) 5%
B) 3.5%
C) 10%
D) 12%
E) 15%