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.

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

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.

they both wanted to stop protestantism, they felt a call in life and it was to strengthen the church. charles used inquisition, philip used army's, charles gave control to outsiders, philip centralized all power.

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