— I rang you at about nine,but there was no reply.

— Oh,that was probably________I was seeing the doctor. [ ]

A. why  

B. when

C. what  

D. that

物探专用电缆的型号中WTYP-200中的P代表（）。

A.绝缘层材料

B.护套材料

C.温度组别

D.插头座代号