Consider the public objections to akion T4

i think the answer is c, rivers.

explanation:

sometimes, borders fall along natural boundaries like rivers or mountain ranges. for example, the boundary between france and spain follows the crest of the pyrenees mountains. for part of its length, the boundary between the united states and mexico follows a river called the rio grande. the borders of four countries divide africa’s lake chad: niger, chad, cameroon, and nigeria.

after defeating german forces in north africa allied leaders turned their attention to "italy," since this was the location that made the most geographic sense before invading northern europe via france. 

japan is located on a chain of islands called an archipelago. it is made up of four main islands and thousands of smaller ones. the terrain is mountainous, which means there is not a lot of good land for farming. because of the geography, the japanese relied on the sea for many aspects of daily life.

the poor lived on the docks by the sea, and the wealthy lived in highly populated urban areas. that is the answer