问题如下：
The principle of “Change in polarity” is about:
选项：
A.Breached uptrend becomes downtrend
B.Breached resistance levels become support levels.
C.Trend reversal when short-term moving average is crossing the long-term moving average.
解释：
B is correct. Change in polarity indicates that breached resistance levels become support levels and breached support levels become resistance level.
老师 这里考察哪个知识点？
