Factors Shifting the Yield Curve

Consider a scenario where a fixed income investor is evaluating the yield curve of a series of bonds with different maturities. The investor notices that the yield curve is upward sloping, which typically suggests a healthy and growing economy. However, the investor is also aware that changes in monetary policy, inflation expectations, and market demand for bonds can significantly impact the construction of the yield curve.

Which of the following factors is most likely to cause a sudden shift in the yield curve, leading to a temporary inversion, even when the overall economy appears to be stable?