Fill in the blank with the most appropriate word:
When people are _______, as long as they hold fast to their language, it is as if they have the key to their prison.

'When people are' should be followed by a noun that defines the people as identifying with something else. Option A is not a noun and will be eliminated. Option B, 'unslaved', is the incorrect spelling of the word 'enslaved' and is also wrong. Option C and option D are both good candidates. Note that a prisoner is not necessarily morally right, and is likely not a victim. Since the sentence talks about the people in a positive light, 'prisoner' will be eliminated. The correct choice should be 'enslaved', which refers to people as victims of enslavement, and, as long as they are holding fast to their language, it is as if they have a key to their prison. The correct answer is option C.