The correct answer is D, because "their" signifie that they are having "their" conversation, and that they own the conversation. C is incorrect because "there" describes where, B is incorrect because "they" describe who, and A is incorrect because "they are" doesn't grammatically or sensibly fit in, so the answer is D.
Well, it will always be important but I suppose it's because it hasn't stopped and I personally doubt it will any time soon. The wrongful incarcerations are still an issue because it can ruin someone's career and life.
