For a transformer with primary turns $400,$ secondary turns $100,$ if $20$A current is flowing through primary, we will get $\_\_\_\_\_\_\_\_\_\_\_$a$\mathrm{.}5$A at secondaryb$\mathrm{.}80$A at secondaryc$\mathrm{.}800$A at secondaryd$\mathrm{.}40$A at secondary