_______ they are twin brothers, they don’t look like each other.

A．Though

B．Since

C．However

D．When

脑脊液鲎珠溶解物试验有助于下列哪种疾病的诊断（）

A.革兰阴性细菌脑膜炎

B.革兰阳性细菌脑膜炎

C.病毒性脑膜炎

D.结核性脑膜炎

E.真菌性脑膜炎