[单选题]
In a transformer, if the)o33zh6:fii g k4el.q rozoa6 primary comz:d j2 h ix4lld gt8 z3p:08k0/wzsxmil contains more loops than the secondary coil t x2zghz0:4swm k8l:8mldi3 px/d 0jzthen it 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.
