Correct Answer: A
Explanation:
The trigger "even more" tells you to stay in the same direction as the clue. "Forced to take an alternate road," "two-hour detour," and "arduous trip" tell you that the journey was difficult. Put a word that means hard or tiring in the blank. Only irksome and onerous fit this meaning. Facile and glib describe something easy, and implacable and immutable describe something that doesn't change.