5. (10 points) The figure below includes plots of three time series, each of length 500, along with their sample ACF plots. Which of these three time series behaves like a white noise? Explain. Note that the x-axis of the ACF plots begin only at lag 1. Series 1 ACF Series 1 LAG ACF Series 2 23- 2010 128 3 ACF Series S ACF Figure 1: The x-axis in the sample ACF plots starts at lag 1