[单选题]
In a transformer, if the pawc4/0tke8r.q +niq f risk ra - +1cc )q5zvxgb)d88pvomary coil contains more loops than the secondary coil then it idp- bqa8)c1s)8kvxr5+ogvc zs a
A. step-up transformer.
B. step-down transformer.
C. either a step-up or a step-down transformer.
D. can not be determined.
