If the Aggregate Price Level at Time T Is Denoted $\pi_{t}=\left(P_{t}-P_{t}-1\right) / P_{t}-1$

If the aggregate price level at time t is denoted by Pt,the inflation rate from time t - 1 to t is defined as

A) $\pi_{t}=\left(P_{t}-P_{t}-1\right) / P_{t}-1$
B) $\pi_{\mathrm{t}}=\left(\mathrm{P}_{\mathrm{t}}+1-\mathrm{P}_{\mathrm{t}-1}\right) / \mathrm{P}_{\mathrm{t}-1}$
C) $\pi_{t}=\left(P_{t}+1-P_{t}\right) / P_{t}$
D) $\pi_{t}=\left(P_{t}-P_{t-1}\right) / P_{t}$