"Can you get tan from a campfire?".

You could if you had a special fire letting out UV light, but if not, you'd probably get burned first.

Explanation:

Fire does emit UV, which causes tanning, but it also emits a lot of other wavelengths, including infrared which is primarily responsible for heating. If you build a really big fire, one that would emit enough UV to tan, it would also emit a huge amount of infrared which will burn you sooner than you getting a tan.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current