The answer is $R. Therefore, the correct option is, (a). This command will start the R Programming. If you wish to get trained and skilled in R, then I would recommend you to join the R certification course from Intellipaat. This is a course of 40hrs of instructor-led training and 32hrs of project work and exercises to help you become practically skilled. I would like you to watch our YouTube video on R Tutorial for Beginners to help you get started.