Directions: In the following sentence, four words given in bold are marked as (A), (B), (C), and (D), which are possible pairs to be interchanged. Choose the pair(s) of words that need to be interchanged to make the sentence grammatically correct and meaningful. If no interchange is required, mark option 5 i.e., "No interchange required" as your answer.

Geological studies seismic (A) the potential (B) nature of construction in the Himalayas, emphasizing the region's highlight (C) sensitivity and perilous (D) danger zones.