Answer:
Vernacular
Step-by-step explanation:
Vernacular is a language and speech pattern that is commonly used by the people in a specific region.
Humanist writers' purpose is to brought up social issues that that observed from their surrounding environment along with day to day activities that the people have to get through. They use Vernacular because it is much easier to digest by the target audience. It help accelerate the spread of social awareness prompted by their writing.