The Greenspan Model Attempts to Estimate the Relative Valuation of the Stock

The Greenspan Model attempts to estimate the relative valuation of the stock market by:

A) subtracting the 10-year Treasury bond yield from the S&P 500 earnings yield.
B) comparing the U.S. T-Bill rate with the E/P ratio of the broad market.
C) subtracting the S&P earnings yield from the yield on a long-term U.S. Treasury bond.
D) subtracting the S&P dividend yield from the 10-year Treasury yield.