How do you evaluate which factor was the most important?

In order to weigh up which factor was the most important you need to look at each factor separately and decide to what extent that effected the problem in question. For example, if you were looking at what factor was the most important in Mussolini's rise to power, you need to establish what allowed him to come into power. Was it Mussolini's skills, was it the King's lack of power which allowed him to take over, was it the support he had from the military etc? When we look at this problem, Mussolini's skills were important, but actually if someone had stopped him he wouldn't have come into power so that is not the most important factor. Looking at his supporters, yes they did give him a platform on which to rise to power, however they did not enable him to take over completely. Who you look at the Kings role, you can see that actually he did have the power to stop Mussolini, but refused to use it effectively. Therefore, the role of the King was the most important factor in Mussolini's rise to power.