Explanations:The question requires understanding the logical connection between the two parts of the sentence. The sentence begins by stating that the people of Nagaland came from various regions including Burma and Tibet a long time ago. The second part of the sentence should logically follow and provide additional information or a contrast to the first part.
The correct answer, "But experts do not," introduces a contrast to the first part of the sentence. It suggests that while the people of Nagaland came from various regions, experts are unable to pinpoint the exact time of their migration. This maintains the logical flow and coherence of the sentence.
Option A, "Experts that do not," does not make sense in the context of the sentence. It disrupts the flow and does not provide a logical continuation. Option B, "Not that experts," is grammatically incorrect and does not fit logically with the first part of the sentence. Option D, "Of which experts do not," does not fit grammatically or logically with the first part of the sentence and does not provide a coherent meaning.
Understanding sentence structure and logical flow is crucial in language comprehension. The correct option should maintain the coherence and logical connection between the two parts of the sentence. In this case, the correct option is "But experts do not," as it provides a logical contrast and maintains the flow of the sentence.