Which of these hold true for a data frame?

It is a two-dimensional objectIt can have different data typesBy default, strings are saved as factorsMust hold elements of the same type

Nice! A data frame is a matrix-like object that can hold different types of variables. By default, strings are saved as factors.

Oh noes! A data frame is a matrix-like object that can hold different types of variables. By default, strings are saved as factors.