我唔識做聽日交嘅功課

obviously, C.
A and B are safety precautions.
D is the way to treat striking back of flame, ie, flame burns in chimney of the burner. this makes the burner very hot, but cannot heat things anymore. as it's very dangerous, it's better to turn off the gas supply immediately to cut the flame. allow it to cool completely before lighting up again. a wetted cloth may help to cool quicker.
C, however, is very dangerous. it is one of the causes of striking back.
remember, close the air hole before lighting up a Bunsen burner, and double-check it.

C is incorrect.

It is difficult and dangerous if lighting a bunsen burner with open air hole.
1. the gas may blow out the match or the gas is so blowing so fast that the match cannot light it.
2. dangerous as it is hard to see the flame when LIGHTING the bunsen burner with a open air hole
3. you only open the air hole when burning something( more energy needed complete combustion)
A and B is precaution
so ANSWER IS (D)

i am afraid the answer by emily is wrong.
according to the process discribe in f4 ARISTO CHEM BK
the using of BUNSEN BURNER should be:
1 CLOSE the air hole
2 light up a match
3 open the gas tap
4 adjust the air hole

therefore, the answer should be C but not D

The answer is C.

D
Because A-C is correct describe what we need to do before using a bunsen burner
while D is difference of what A-C talk about