This site has no system to allow "alternative moves" to my knowlodge. It deletes questions with multiple answers, or it tries to carefully chooses where a question ends so two alternative moves
Alternatives in Tactics Trainer

But then this problem should be removed, I think...
It would be removed or edited if they were equal solutions. However the line played is a quick mate in 4 (knight block then mate). However 4. Qf5 Nxg7 5. fxg7+ Kg8 6. gxf8=Q+ Kxf8 7. Qxd7; yes you are dominantly ahead, but you have delayed mate a little and allowed the possibility that you fall deftly ill and can't finish the game. Yeah its splitting hairs, but tactically the line offered is the best.
http://www.chess.com/tactics/server.html?id=24718
In this problem, 4. Qf5 clearly wins.
Are there alternatives on this page?
On ChessTempo there are, and on Chess Tactics Server there aren't. How is it here?