다음은 수소와 산소가 반응하여 물이 합성될 때의 질량 관계를 나타낸 것이다. 합성되는 물의 양이 같은것 끼리 바르게 짝지은 것은?

                                수소기체        산소기체
                       A           4g              40g
                       B           6g              24g
                       C           8g              24g
                       D           4g              56g
                       E           6g              56g

                1.AB     2.AC    3.CD   4.BC    5.AE
                                                                       답은.4번이라네요
0제생각에는  일단물의 성분비는 2:1:2 니깐 질량무시하고 
수소기체량이 같은거끼리 묶으면 A와D B와E 인거같은데 질량비 1:8:9인건아는데 모르겠네요...
이해하기쉽게 구체적으로 알려주세요..