Language rules that govern how words can be combined to form meaningful phrases and sentences

Syntax

Syntax is a set of principles, rules and processes that dictate the structure or word order of a language.

Syntax is also applied to the study of the rules of language structure and sentence formation.

The correct answer is a. when they started making tools that will them in cultivating lands, they could raise crops and that made them attached to one place for a longer period of time. after that, they started domesticating animals and building their own permanent settlements that resemble the ones we have today.