Question

The definition of frontier is the outer limit of what is known or explored. a landform that makes travel difficult. the border between two states. a river that flows between countries.

Answer 1

A. the outer limit of what is known or explored

Step-by-step explanation:

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Answer 2

The correct answer option is C. the border between two states.

Step-by-step explanation:

Frontier is defined as the border between two states.

The word frontier is a French term which means 'borderland'.

In other or simpler words, frontier is the political and geographical area which is near by or beyond a specific boundary separating the two countries.

Therefore, the correct answer from the given options is: the border between two states.