z (3} ARMA (p, q} log Model order (0.0) 0.932 (1, 0} 0.884 (0, 1} 0.902 (1, 1} 0.838 (2, 1} 0.801 ( 1, 2} 0.82 1 (2, 2} 0.?89 (3, 2} 0.??3 (2 3) 0.?82 (3, 3} 0269 i. What is the 'optimal' model order? (lUmarks) ii. How can one determine if the order you suggested for (i) above is in fact appropriate? (2marks) h) Why is it important to test for non-stationarityr in time series data before attempting to build an empirical model? (Smarks) e) How can one determine if a given series is stationary? (4marks) d) How can a nonstationary,Ir time series be transformed into a stationery series