Human systems, one of the six essential elements of geography, can best be described as the study of
a.
where people live and what cultures they create
b.
where things are located in relation to one another
c.
how people group places into regions
d.
how the earth’s natural environments are changing

A. Where people live and what cultures they create

Explanation:

Human systems, one of the six essential element of geography, can best be described as the study of where people live and what cultures they create.

Geography comes from the Greek "geo", which means earth, and "graphy" which means drawing. At the beginning geography was only the study of maps, but in time geography becomes the study of 6 essential elements:

Human System is the study of people in a certain environment that surrounds them. It observes how cultures and behaviors are defined by the location in which they live.

The world in spacial terms is referred to the study of maps and everything that is connected to the spacial contest. 

Places and regions is about how people create culture in particular places called regions.

Physical system is about study of earth in a physical way like volcanoes and oceans.

Environment and society study how we interact with nature and we adapt the natural system to fit our needs.

And last but not least the use of geography teaches people how to connect all these elements into a coherent frame to study the earth and humans.

A.  Where people live and what cultures they create

Explanation:

According to geographers, the physical properties located on the surface of the earth and the human surrounding, it is explored.

Geographers also are in charge of examining how culture interacts with the surrounding environment, and the locations have impacted people while seeking to understand the situation and how they affect people. However, the Greeks were not the only people who had an interest in studying Geography, yet many people from different societies are trying to understand different parts of the world.