能否解释一下为什么选B

问题如下：

选项：

A.Slow economic growth expectation

B.Central bank engaging in expansionary monetary policy

C.High inflation expectation

解释：

B is correct. A central bank engaging in expansionary monetary policy might cause the yield curve to steepen by reducing short-term interest rates and thus cause greater volatility in short-term bond yields to maturity than in longer-term bonds.

A is incorrect because slow economic growth expectation will have more impact on the longer-term bond yield volatility.

C is incorrect because high inflation expectation will have more impact on the longer-term bond yield volatility.

考点：yield volatility

解析：央行实施扩张性货币政策，短期利率下降，导致收益率曲线变陡，从而导致短期债券利率波动性大于长期债券利率波动性。