A. If you believe "reversion to the mean", you should be bullish about stocks.
Why?
From the following chart, you can see that stocks over the past 15 years have performed poorly - average 3.8% annualized return, worse than the 15-year period that ended in the bear market of 1974.
For the believers of reversion to the mean, this indicates much higher return for the next 15 years for the stocks.