As shown in several fire safety signs, it is forbidden to set off firecrackers in _ _ _ _ _ (fill in the serial number, the same below); Smoking is forbidden in _ _ _ _ _

A is a flame, which indicates that it is easy to burn and flammable items.

b is a sign that a pile of flammable items is prohibited and it is forbidden to pile up flammable items.

c is a sign that explosives are prohibited.

d is a sign that matches are prohibited from burning and naked flames are prohibited.

e is a sign that a burning cigarette is prohibited and smoking is prohibited.

f is a sign that smoking is prohibited. E