The R package openair is used for the analysis of air pollution data.

Which function prints out the function call stack after an error occurs?

 __________ prints out the function call stack after an error occurs. 

Which of the following function carries out a chi-square test?

Which of these is a systematic way to examine how much time is spent in different parts of a program?

What is the output of the R command getOption("defaultPackages")?

The group_by() function is used to generate summary statistics from the data frame within strata defined by a variable.

Which R package provides extensions to the distr package and additional statistical functions like variance, standard deviation, interquartile range, median absolute deviation, median, skewness, and kurtosis?

When do we use the .rda file extension when saving R objects?