In the Specification of Adaptive Expectation Used in the Dynamic $\pi$

In the specification of adaptive expectation used in the dynamic model of aggregate demand and aggregate supply, at time t the expected inflation rate at time t + 1 is:

A) $\pi$ _{t - 1.}
B) $\pi$ _t.
C) $\pi$ _{t + 1.}
D) $\pi$ _{t + 2.}