[单选题]
In a transformer, if the. xj)d4 k/1bmelhoiaoxz ch:d:2;k*f secondary coil contains more loops than the pribl;f(s gf jc 1hiak-;3mary coil then itjhb1ag(;kf-3sf l; c i is a
A. step-up transformer.
B. step-down transformer.
C. either a step-up or a step-down transformer.
D. can not be determined.
