Explanation:
AL16UTF16 is a 2-byte, fixed-width Unicode character set, which is also referred to as UTF16 or UCS2. The ASCII English character set is assigned the first 128 values from 0 (0X00) through 127 (oX7F) in Unicode, which translates to 1 byte. Even though AL16UTF16 uses one more byte than UTF8 for ASCII character representation, it is still faster because it uses fixed-width encoding as opposed to UTF8, which uses variablewidth encoding. UTF-16 encoding enables easier loading of multinational data. It uses a fixed-width multibyte encoding sequence.
Incorrect Answers:
3: Asian characters are represented in two characters because UTF16 is a 2-byte, fixedwidth Unicode character set.
4: It uses a fixed-width multibyte encoding sequence.
5: European characters are represented in two bytes because UTF16 is a 2-byte, fixedwidth Unicode character set.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 266-278
Chapter 5: Language Enhancements
Oracle 9i New Features, Robert Freeman, p. 139-146
Chapter 5: Miscellaneous Oracle9i Features and Enhancements

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