Which type of diffusion promotes the spread of an idea or trait through hierarchy?

The correct choice is hierarchical diffusion, which refers to the process through which an idea or trait spreads through a system based on levels of influence, typically from a higher level to a lower level, such as from leaders or celebrities to their followers. This type of diffusion often occurs within structured social systems where individuals or groups, usually perceived as having more power or status, adopt a particular idea or practice first. Once adopted, this idea can then spread down to others within that hierarchy or from one node to another.

For instance, a new fashion trend may initially be adopted by top designers or influencers before trickling down to the mass market. This hierarchical relationship dictates the order and speed with which the idea disseminates, making it distinct from other diffusion types, which do not emphasize this structured approach. The other forms of diffusion, although they involve the spread of ideas, do not specifically focus on a hierarchical process.