Dataset $$trees$$ has three measurements on each of $31$ black cherry trees: Girth $($diameter in inches$),$ height in feet, and volume in cubic feet. The data can be imported using the function: data$("$trees$")$

a$)$ Using the pairs function, draw the pairwise scatter plot in R to identify strong correlation and any outliers.

b$)$ Perform a principal component analysis of this data in R$.$ Use the biplot to show the first principal component captures the strong correlation. Interpretate the results using scree plot.