The dataset airquality in the R datasets package includes information on daily air quality measurements in New York, May to September 1973. The variables included are mean ozone levels at Roosevelt Island, solar radiation at Central Park, average wind speed at LaGuardia Airport, and maximum daily temperature at LaGuardia Airport;

see help(airquality) for details.

(a) Load the dataset into R.

(b) Investigate the structure of the dataset.

(c) Plot each of the four series mentioned above using the plot() command in R; see help(plot) for details and examples.

(d) Comment on the behavior of the four series. Do you see any issues that may require special attention in developing a time series model for each of the four series.