Answer:
The correct answer is:
nation (b)
Explanation:
A nation refers to a group of people with some common features such as language, history, territory, ethnicity, religion, and culture. Recently, nations have been described as being political rather than ethnic groups. Example of nation is South Korea, because almost everyone here speak the Korean Language.
The term nation is usually confused with a state which is a group of people with mainly similar centralized political entities or country which also describes a politically bound group of people.
Note also that if a nation incidentally is made up of just one state, it is called a nation-state.
Now, defining the other terms in the options;
a multi-state nation is a nation composing of several states, even though the nation operates many states they have similar cultures. For example their language an example here is The Unites States of America.
While, a multinational state is an autocrat state, occupying a territories of more than one nation. They may have many languages or cultures. Examples are Iraq, Brazil, Canada etc.