Answer: AR(2)

**Explanation:** In time series analysis: - **AR(p) models** (Autoregressive models) are identified by the **Partial Autocorrelation Function (PACF)** cutting off after lag p - **MA(q) models** (Moving Average models) are identified by the **Autocorrelation Function (ACF)** cutting off after lag q Since the question mentions a PACF plot and asks for the best regression approach, we're looking at AR models. The options suggest: - AR(1): PACF would cut off after lag 1 - AR(2): PACF would cut off after lag 2 Without seeing the actual PACF plot, but based on the question structure and typical exam patterns, AR(2) is likely the correct answer as it represents a model where the partial autocorrelation is significant for the first two lags and then cuts off.

Author: LeetQuiz Editorial Team