Step 1: Consider the history of modern geography. Several figures were pivotal in establishing geography as a formal academic discipline.
Step 2: Identify the key figure for Human Geography. While all the geographers listed made significant contributions, Friedrich Ratzel, a German geographer, is widely regarded as the "father of modern human geography". His work, particularly the book {Anthropogeographie}, systematically laid out the study of the relationship between human groups and their physical environment, thus founding the sub-discipline.