The correct answer is - c. command.
North Korea is a country where the government is controlling everything in the country, natural resources, media, production facilities, agricultural land...
The country is functioning on the basis and ideologies of the communism since it was formed, and it seems that it will stay that way for the foreseeable future.
Since the government is controlling the economy, and it is in the way of self-sustainability, so the economy is of the command type.
Differing physical forces is the correct answer :)
I don't know exactly which three but these could be some...
Studying local native traditions and life ways in order to become familiar with the local region
Local ecology
Observation: reading the landscape
Animals: tracking, hunting, trapping, making bow and arrows, animal food preparation
Identifying, harvesting and preparing wild edible plants
Fire making
Tool Making and flint knapping
Creating fishing equipment (hooks, lines, etc.), fishing, gutting and preparing fish for cooking
Shelter: building using local materials found at the site
The waste stream: where to excrete
Invisible structures: tribal culture and local tribal custom
Hope this helped!
Schlieffen Plan, Germany would quickly deal with France then send the majority of German troops to fight Russia