What is the output of this program? import java.util.*; class properties { public static void main(String args[]) { Properties obj = new Properties(); obj.put("AB", new Integer(3)); obj.put("BC", new Integer(2)); obj.put("CD", new Integer(8)); System.out.print(obj.keySet()); } }

• A. {AB, BC, CD}
• B. [AB, BC, CD].
• C. [3, 2, 8].
• D. {3, 2, 8}