Sam, who owns a carpentry shop, discovered that with 4 laborers he could produce 18 cabinets per day. With 5 laborers he produced 25 cabinets and with 6 laborers he produced 36 cabinets. What was the MPP of the 6th laborer?
A) 11 cabinets
B) 7 cabinets
C) 36 cabinets
D) 9 cabinets