Historically, empirical researchers find that firms with high book-to-market ratio tend to earn higher returns on average. Here, book-to-market ratio is defined as the ratio of book value per share to market value per share, as what we have learned in Ch3. Suppose you notice that stock market participants who believe in this evidence and invest heavily on firms with high book-to- market ratio all earn abnormally higher returns. At this case, would you suggest that the market is at the semi-strong form or at the weak form? Why