Question

what defines a nation?
a group with a shared political system
a territory with internationally recognized borders
a group with a shared identity, culture, language, or history
a political entity with a standing military

Explanation:

A nation is typically defined by a group of people who share common elements such as identity, culture, language, or history. While political systems, territorial borders, and military presence can be aspects of a state (which is a political entity), the core defining feature of a nation lies in the shared cultural and identity - based characteristics among its people.

Answer:

A group with a shared identity, culture, language, or history.