How do i get arguments for my essay.

I know how to structure an essay but ive never truly been shown how to get 3 arguments from a question. An example of this is, if i were asked "How significant was the role played by political parties in influencing government policy 
in the years 1871 to 1890?". Im not even sure what 3 arguments are possible in this. The only i can think of is, yes they were significant or no they weren't. But even then, those arent strong arguments.