Columnist: Over the last 20 years the demand in North America for Japanese-made automobiles has increased, whereas the Japanese demand for North American-made automobiles has been stagnant.
Your task
Find the assumption the argument requires in order for its conclusion to hold.
Common trap
Answers that would help the argument but aren't strictly required (sufficient, not necessary).
Winning move
Negate each choice — the right one breaks the argument when negated.