[单选题]
In a transformer, if the pb1;gk2-m.-f vqdazn z)w /ygbrimary coilse9m,l6oviibbhi 3 diz0 ;;a0z2v :po contains more loops than the secondary coil tie aloz6, pvsh2ozbvbi;:0i3 i90 md;hen 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.