In Java, every object has an equals and a hashCode method that is used, among other things, by the standard Collections library. By default both are based on an objects memory location, but best practice dictates that they should be overridden to be dependent on the objects state. The rule that should be followed when doing this is: if two objects are equal, then they should have the same hash code value. Which of the following situations would be permissible and which would not under this rule? Provide a brief justification for each.

(a) Two objects have the same hash code and are equal (b) Two objects are equal but have different hash codes

(c) Two objects have the same hash code but are not equal (d) Two objects have different hash codes and are not equal

(please give every explanation for each one, do not just give an option)