The primary data structure behind almost all R operations is the vector, and a collection of vectors is used to form a data frame. Which of the following statements CORRECTLY describe vectors and data frames in R$?($There may be more than one correct answer.$)$

The values within any vector must always be of the same data type. I.e$.,$ the "vector" $[23"$a$"1\mathrm{.}5]$ is invalid and cannot exist as a variable in R$.$

It is possible for a vector of integers to contain the special "NULL" $($missing value$)$ data type. E$.$g$.,$ c$(4,3,$ NULL, $1)$ is valid code.

Data frames contain vectors, but tibbles do not.

An R data frame is a tibble.