She came back with her two friends,        .

A．neither of them are doctors

B．neither of them is a doctor

C．neither of whom are doctors

D．neither of whom is a doctor

某化工厂一男性，从事染料生产工作，工龄25年，因尿血住院检查，可疑患有膀胱癌。可能由下列何种物质引起

A．氯乙烯
B．联苯胺
C．石棉
D．苯
E．铬酸盐