The correct answer is C. Intracity
Explanation:
A boundary refers to an imaginary line that limits a specific place, this can be linked to geography, for example, a river that separates two places or can be the result of historical processes, as some borders are created based on colonization of the territories, conflicts, agreements, etc. Additionally, boundaries are classified as internal if they are under the national level, in the U.S. this includes state boundaries, counties, municipalities, cities and intracity. Moreover, from these, intracity is the smallest type of boundary because they limit areas within cities and therefore are much more specific than cities divided into intracities while states and counties divided into multiple cities.