The correct answer is: D. all of the mentioned.

The packages xlsx, xlsc, and read.sheet can all be used to read Excel data into R.

The package xlsx is the most recent and recommended package for reading Excel data. It is based on the open-source readxl package, and it provides a simple and efficient way to read Excel data into R.

The package xlsc is an older package that is still supported, but it is not recommended for new development. It is based on the read.xls function from the base package, and it is not as efficient as the xlsx package.

The package read.sheet is a low-level package that can be used to read data from any type of spreadsheet file, including Excel files. It is not as user-friendly as the xlsx package, but it can be useful for reading data from files that are not in the standard Excel format.

Here is an example of how to read an Excel file into R using the xlsx package:

“`
library(xlsx)

Read the Excel file into R

data <- read_excel(“data.xlsx”)

Print the first few rows of the data

head(data)
“`

This will print the first few rows of the data from the Excel file data.xlsx.