4. Examine the following four plots below which are based on quarterly data for the gold price from 1976 quarter 1 to 2012 quarter 4. The first plot is the log of the nominal gold price expressed in dollars per troy ounce. (a) Interpret figure 1. (b ) What quantity is being plotted in figure 2? Interpret the plot. (c) What can you tentatively conclude from figure 3? (d Explain figure 4 with reference to figure 2