The correct answer is: All of the mentioned.

Slidify is a package that allows you to create interactive slideshows from R Markdown documents. It can be used to add quizzes, RCharts, and Shiny apps to your slideshows.

Quizzes can be added to slidify using the quiz() function. This function takes a list of questions and answers as input and creates a quiz that can be answered by the user.

RCharts can be added to slidify using the rchart() function. This function takes an R code object as input and creates a chart that can be displayed in the slideshow.

Shiny apps can be added to slidify using the shiny() function. This function takes a Shiny app object as input and creates a link to the app that can be clicked on by the user.

Here is an example of how to add a quiz to a slidify slideshow:

```r library(slidify)

Create a list of questions and answers

questions <- list( question = "What is the capital of France?", answer = "Paris" )

Create a quiz

quiz <- quiz(questions)

Add the quiz to the slideshow

slideshow(quiz) ```

Here is an example of how to add an RChart to a slidify slideshow:

```r library(slidify)

Create an R code object

code <- rnorm(100)

Create an RChart

chart <- rchart(code)

Add the chart to the slideshow

slideshow(chart) ```

Here is an example of how to add a Shiny app to a slidify slideshow:

```r library(slidify)

Create a Shiny app

app <- shinyApp( ui = fluidPage( textOutput("output") ), server = function(input, output) { output$output <- renderText(paste("Hello, world!")) } )

Add the Shiny app to the slideshow

slideshow(app) ```