Explanation: This question is asking about plausible reasons the source mentions the Buddhist presence in Persia in the third century (C) E. Buddhism was a religion largely spread by merchants, so look for the choice that emphasizes this aspect. Choice (A) invokes a memory of Roman persecutions of Christians, not trade, so eliminate it. Choice (B) is demonstrably false because Buddhist doctrine largely does not include an apocalyptic message, so eliminate (B) as well. Choice (C) does mention trade routes with India, where Buddhism originated, so keep it. Choice (D) is not mentioned by the passage, as Kerdir is proud of quashing practicing Buddhists within the empire; eliminate (D). The correct answer is (C).