Suppose numeric vectors X, Y, and Z are all of the same length. Which R command will create a matrix with rows X, Y, Z?

Which R command is used to merge two data sets X and Y by the variable "ID" that includes all records from both data sets?

Which object class can contain multiple unrelated object classes of potentially different sizes?

I want to use the sort() function, and I see in the help file that I my sort "an R object with a class, or a numeric, complex, character, or logical vector." Given this guidance, which is a valid call to sort()?

Which is NOT a valid R function for obtaining the residuals from a simple linear regression model of X predicting Y?

Let X be a 3x4 matrix with non-zero values. The result of: > apply(X, 2, mean), is:

Which of the following is NOT one of R's basic vector types?

Which one is the correct expression regarding outer product of two arrays?

Which R code subsets a matrix Y to only those records (rows) where a variable x (in Y) is less than 100?

What R function can be used to tabulate values of categorical variable Y (columns) by categorical variable X (rows), including missing values?

All of the following will directly display the help file for the plot() function except: