Final answer:
The correct adjective to complete the sentence about a route taken to avoid traffic jams is 'circuitous', as it describes a path that is longer and less direct, often used to avoid obstacles like traffic.
Step-by-step explanation:
The sentence you provided is seeking an adjective that best completes the thought about a route that is taken to avoid traffic jams. The correct answer to this question is: a) Circuitous.
A circuitous route refers to a path that is longer than the most direct way because it goes around something or takes a winding course. This makes sense in the context because you are avoiding traffic jams, which often means taking an alternative, and potentially longer, route. On the other hand, 'direct' would imply a straight route, 'scenic' would suggest a route with attractive views, and 'arduous' would describe a route that is difficult or tiring, which do not seem to align with the context provided.