Question

Which condition must be true for a nation to exist?
A.
All of the people must speak the same language.
B.
A single religion must unify the citizens of the country.
C.
At least a million people must live within the borders of the country.
D.
The country must be sovereign and handle its own affairs.

Answer 1

In order for a Nation to exist:

There must be a (normally at least 10,000) group of people

There must be similar traits in Culture (tradition, architecture, clothing.. etc. etc.)

However a state (which I assume you meant; often confused with Nation or State) requires the following:

Sovereignty- Economic independence, Military independence, Political stability

Answer 2

D. The country must be sovereign and handle its own affairs.