Third factor in Fama French three factor model is ratio which is classified as

book to market ratio
market to book ratio
company to industry ratio
stock to portfolio ratio

The correct answer is: B. market to book ratio

The Fama-French three-factor model is a model that describes the cross-section of stock returns in the United States. The model states that the excess return of a stock can be explained by three factors: market risk, size risk, and value risk.

The market risk premium is the additional return that investors demand for holding risky assets over risk-free assets. The size risk premium is the additional return that investors demand for holding small-cap stocks over large-cap stocks. The value risk premium is the additional return that investors demand for holding stocks with low book-to-market ratios over stocks with high book-to-market ratios.

The market-to-book ratio is a measure of a company’s valuation. It is calculated by dividing the market value of a company’s equity by its book value. A high market-to-book ratio indicates that investors believe that the company is worth more than its book value. A low market-to-book ratio indicates that investors believe that the company is worth less than its book value.

The market-to-book ratio is a useful tool for investors to use when evaluating stocks. However, it is important to remember that the market-to-book ratio is only one factor to consider when making investment decisions. Other factors, such as a company’s earnings growth rate and profitability, should also be considered.

The other options are incorrect because they are not measures of valuation. The book-to-market ratio is a measure of a company’s financial health. The company-to-industry ratio is a measure of a company’s size relative to its industry. The stock-to-portfolio ratio is a measure of a stock’s volatility relative to its portfolio.