Question: Determining the age of trees is of interest to both individual land owners and to the Forest Service of the US Department of Agriculture. The simplest (though not the most reliable) way of determining the age of a tree is to use the relationship between a tree's diameter at breast height (4-5 ft) and age. Read the data on the average age of three types of trees at different diameter values into the data frame ad by ad = read.table("TreeDiamAAge3Stk.txt", header = T). Then, use the commands attach(ad); plot(diam, age, pch = 21, bg = c("red", "green", "blue")[unclass(tree)]); legend( x = 35, y = 250, pch = c(21, 21, 21), col = c("red", "green", "blue"), legend = c("SMaple", "ShHickory", "WOak")) to plot the data and add a legend. Comment on any difference in the growth patterns of the three different trees.