Concept:Identify which word pair, when interchanged, makes the sentence logically consistent and grammatically correct.
Explanation:The original sentence says a harmful ("detrimental") investment proved profitable ("lucrative") because high taxes eroded profit margins.
High taxes reducing profit margins would make an investment less profitable, not more.
Therefore, the words "detrimental" and "lucrative" must be swapped.
After interchanging A and B, the correct sentence is:
"The lucrative investment proved to be detrimental in the long run because of the exorbitant taxes that eroded the initial profit margins."
This makes perfect sense: a profitable investment turned harmful due to heavy taxes.
So, the required pair is A and B.
Answer:Option D (A-B).