单项选择题

A.(C5~C7)/(C1一C4)和(C5~C7)/(C3~C4
B.(C1~C4)/(C1一C5和(C5~C7)/(C1~C5
C.C1-C4的总含量和i-C4/n-C
D.C1~C4的总含量和(C2~C6)/(C1~C4