Explanation

This question tests the understanding of market efficiency forms:

1. Weak-form efficiency: All past price and volume information is already reflected in stock prices. Technical analysis (using historical price patterns) should not generate abnormal returns.

2. Semi-strong-form efficiency: All publicly available information is reflected in stock prices. Both fundamental analysis and technical analysis should not generate abnormal returns.

3. Strong-form efficiency: All information (public and private) is reflected in stock prices. No investor can earn abnormal returns.

Key Analysis:

• The analyst is using a seasonal pattern (price declines in spring, increases in fall) which is based on historical price data.
• If the analyst can consistently earn abnormal returns using this historical price pattern, it means the market is not weak-form efficient.
• Since weak-form efficiency is the most basic form of market efficiency, if the market fails even this test, it is considered inefficient.

Why not weak-form efficient? Because weak-form efficiency states that historical price patterns should not provide opportunities for abnormal returns.

Why not semi-strong-form? Semi-strong-form efficiency is a stronger form that includes weak-form efficiency. If the market fails weak-form efficiency, it automatically fails semi-strong-form efficiency as well.

Conclusion: The ability to consistently earn abnormal returns using historical price patterns indicates the market is inefficient.