Astronomer: Astronomical observations in many areas have become useless because light from nearby cities obscures the stars Many people argue that since streetlights are needed for safety, such interference from lights is inevitable.
Your task
Describe how the argument proceeds — the technique it uses to reach its conclusion.
Common trap
Answers that describe a method the argument doesn't actually use.
Winning move
Track the role each statement plays, then match that to the choice describing the same moves.