Question

___ is used to extract elements of a list or a data frame and can only be used to extract a single element - the class of the returned object will not necessarily be a list or data frame.

A. $
B. []
C. [[
D. None of the above

Answer 1

The [[ operator is used to extract elements of a list or a data frame and can return a single element or a sublist.

Step-by-step explanation:

The correct answer is C. [[.

The [[ operator is used to extract elements of a list or a data frame in programming languages such as R. Unlike the $ operator, which extracts a single element and returns the class of that element, the [[ operator can extract a single element or a sublist, and the class of the returned object may not necessarily be a list or a data frame.