That made no sense so I followed your link and found that C is uncontrived not contrived, which then makes perfect sense.
Every option has either 2 words that make no sense, or one word that makes no sense with "her movements were natural" and one that does. Only option C has two words which make sense with both. This question is just basic English comprehension and should be on every exam.
Sorry, I had seen this elsewhere and it was incorrectly transcribed. You are correct that the linked page shows "uncontrived" for C. That makes the question less bad though still a bit stilted.
Every option has either 2 words that make no sense, or one word that makes no sense with "her movements were natural" and one that does. Only option C has two words which make sense with both. This question is just basic English comprehension and should be on every exam.