Which one of the following statements can be used to extract the last five characters from any string variable str?

The selected statement effectively extracts the last five characters from any string variable by utilizing the substring method, which takes two parameters: an initial index and a final index (exclusive).

In this case, str.length() - 5 computes the starting index to be five characters before the end of the string. The second parameter, str.length(), specifies that the substring should include characters up to the very end of the string. This means the characters from index str.length() - 5 up to but not including str.length() are returned, which are indeed the last five characters of the string.

Other statements do not correctly specify the indexes needed to extract the last five characters. For instance, using a starting index and a length, as might be interpreted in some options, would not produce the desired result. The correct syntax requires the first index to denote where to start and the second to denote where to stop, making choice A the appropriate one for this operation.