Which statement extracts the last 10 characters from the string variable str?

The statement that extracts the last 10 characters from the string variable str is correctly represented by the option that uses the substring method with the parameters defined as str.length() - 10 and str.length().

In this context, the substring method is used to retrieve a portion of the string. The first parameter is the starting index, and the second parameter is the ending index (exclusive). The length of the string is obtained using str.length(), which provides the total number of characters in the string.

By calculating str.length() - 10, you determine the starting index for the last 10 characters. For example, if str is "Hello, World!", the length is 13, which means str.length() - 10 equals 3. Thus, str.substring(3, 13) returns "lo, World!", encompassing the last 10 characters.

Since the other options either do not set the starting index correctly to get the last 10 characters or misuse the substring method's parameters, they do not retrieve the desired segment of the string.