Which of the following is not a valid mode to open a file?

A. ab

B. rw

C. r+

D. w+

Correct Answer is :

B. rw

Explanation

'rw' is invalid file mode in python. where 'ab' mode is used to open a binary file in append mode, 'r+' is used to read and write both and 'w+'  is also used to write and read both operation.