A、All of the assert statements are used appropriately.

B、Only the assert statement on line 12 is used appropriately.

C、Only the assert statement on line 15 is used appropriately.

D、Only the assert statement on line 18 is used appropriately.

E、Only the assert statements on lines 12 and 15 are used appropriately.

F、Only the assert statements on lines 12 and 18 are used appropriately.

G、Only the assert statements on lines 15 and 18 are used appropriately.