The forty-fifth challenge is 'your favourite acoustic version of a song'.
I immediately thought of anything by Jeff Buckley but his songs are beautiful even when not acoustic.
My second thought was Lady Gaga as anything acoustic by her shows her true talent and is beautiful. I don't like Lady Gaga's song normally so that rules that out.
I then remembered the amazing version of 'Angel' that Pink and Sarah McLachlan did at some awards show. Seriously amazing. Beautiful. Wonderful. Inspirational.