[单选题]
In a transformer, if c.z- jvoterv4 uv8, )qthl;cjo bn ;+nwbd7v59e e primary coil contains more loops than the secondary coil then it is bl;v7djo n ncw;9+ e5ba
A. step-up transformer.
B. step-down transformer.
C. either a step-up or a step-down transformer.
D. can not be determined.
