The prices _____ up all the time and no one knows when it will become stable. [ ]

A. had gone

B. have been going

C. have gone

D. had been going

按照《电气装置安装工程电气设备交接试验标准》规定，电气设备进行交流耐压试验时，加至试验标准电压后的持续时间，无特殊说明时，应为3min。