用丝绸摩擦过的玻璃棒去靠近甲、乙两个轻小物体，结果甲被排斥、乙被吸引。由此可以判定                                                                 

A．甲一定带正电，乙一定带负电

B．甲一定带负电，乙一定带正电

C．甲一定带正电，乙不带电或带负电

D．甲一定带负电，乙不带电或带正电