What is the most unifying musical factor in the Fifth Symphony?

Answer 1

I'm going to assume you mean Beethoven's Fifth Symphony. The most unifying factor of Beethoven's fifth is the cyclical nature of the multi-movement piece. It features a reoccuring motif that is rhythmic rather than melodic. The recognizable rhythm: short, short, short, long, is a rhythm that exists all throughout the symphony (which is very strange and at the time, unprecedented). Most movements of a symphony are not connected. Beethoven used his Fifth Symphony to bridge the gap between movements. In arguably every movement of the Fifth (a little less in the 2nd movement) one can hear this unifying rhythm that connects the symphony nicely.