Option (iv) 'all the above' is correct. According to the textbook context, an arithmetic line graph (also called time series graph) 'helps in understanding the trend, periodicity, etc., in a long term time series data.' The term 'trend' corresponds to option (i) 'long term trend'. The term 'periodicity' encompasses both 'cyclicity in data' (option ii) and 'seasonality in data' (option iii), as both are forms of periodic patterns. Additionally, the use of 'etc.' in the textbook statement indicates there are other aspects beyond trend and periodicity that can be understood through arithmetic line graphs. Therefore, all the given options are correct.