Great light...so bright...pure white. Also love the deep red to fill the image. But what is it that is being dropped in the glass? It almost made too big of a splash to even notice the splash...if that makes sense. If it had been a smaller object and the splash would then in turn be smaller and would be stronger, in my opinion. Like a small grape right in the middle making a perfect splash and having the rest of the glass pretty much undisturbed would have made for a stronger image...again in my opinion. I hope I have made the slightest bit of sense...if not ask and I'll try and explain again...then again you might just want to disregard everything you've just read anyways. Technically it's a well shot photo...great job on that merit.
Looks like it's a comment I am going to use widely - but how are we to tell if there was a single light source without being experts on studio lighting? I am not and ready to state this. This picture has an impression of broad, and therefore omnidirectional light and seems to be contradicting the challenge. Nice shot nevertheless.
Okay for high key but doesnt really do much for me. I dont think it really demonstrates the use of a single light source - not to say you didnt use just one.