I think Answers 1 and 3 are correct. answer 5 is incorrect because the bean class should have a public constructor WITH-OUT any arguments.The option 5 says it so. Please look at the option 5 again this way:
5) A stateful session bean class DOES NOT have to define a NO-argument public constructor.
If would be correct if it says, "A stateful session bean class , have to define a NO-argument public constructor.