Of all the ways that renaissance society was hierarchically divided, what was regarded as the most "natural" distinction and therefore the most important one to defend?

Gender

Explanation:

Renaissance was a period of European history that was very disputed.This period was a hierarchal age and the place of a person in the society was determined by the class that he/she was born into it.However, the hierarchy was not limited to just rank but also included gender which was defended by revolutionary women as gender was considered as a natural distinction. Thus, revolutionists in the process of equalisation wanted to defend gender the most. 

4, two dominant and two recessive