What is a data frame in R?

A data frame in R is a table-like structure used for storing data. It is a key data structure that allows you to store data in rows and columns, where each column can have a different data type (such as numeric, character, or factor). This format makes data frames particularly useful for organizing datasets, as they resemble spreadsheets or SQL tables, allowing for efficient data manipulation and analysis. Data frames enable you to perform operations such as subsetting, filtering, and applying functions to individual columns, making them integral to data analysis in R. They also support various data analysis tasks, such as modeling and statistical computation, by providing a coherent framework for handling complex data.

While the other options mention relevant concepts in data analysis and R, they do not accurately define what a data frame is. Data visualization methods and statistical testing functions contribute to data analysis but do not describe the structure used for data storage, which is the primary characteristic of a data frame.