Concept:Find the pair of words that, when interchanged, make the sentence grammatically correct and logical.
Explanation:The original sentence: While the daunting (A) instructions were meant to simplify (B) the assembly process, they only served to confuse (C) the users, making the task more convoluted (D).
"Daunting" means intimidating, so it does not fit with "instructions" here.
"Convoluted" means complicated or difficult to follow, which fits "instructions" perfectly.
Also, "daunting" fits better with "task" in the latter part of the sentence.
Thus, interchanging A and D gives: While the convoluted instructions were meant to simplify the assembly process, they only served to confuse the users, making the task more daunting.
This sentence is grammatically correct and meaningful.
No other pair works as well.
Answer:A-D, i.e., option 1.