单选题
编号：2690486
1. Which of the following trading strategies is most likely using the change in polarity principle?
- A.Smith enters an order to buy a stock if the price decreases to 25,which had been the stock's historical high before it rallied to its current price of 30.
- B.Jones buys a stock when a momentum oscillator indicates an oversold condition and sells the stock when the oscillator indicates an overbought condition.
- C.Johnson buys a stock when its 5-day moving average crosses above its 20-day moving average and sells the stock when the 5-day average crosses below the 20-day average.