How to shoot a silhouette

HI All,

I am planning to film a quickie viral in silhouette. Not shot in this way before and so looking for a bit of advice. The idea is to film 2 people carry out some simple actions behind a screen, but the images have to be pretty sharp. Shooting on Sony EX3

Would i be best to...

A) Use a large piece of trace or thin paper and wham some lights behind them in a dark room

B) shoot against green screen, then invert image in FCP and frame it afterwards - but this might look contrived?

C) something completely different and more obvious that I am overlooking

Thanks,

eve