Which of the following statements about declaration are true？（）         

• A、 Declaration of primitive types such as boolean， byte and so on does not allocate memory space for the variable.
• B、 Declaration of primitive types such as boolean， byte and so on allocates memory space for the variable.
• C、 Declaration of nonprimitive types such as String， Vector and so on does not allocate memory space for the object.
• D、 Declaration of nonprimitive types such as String， Vector ans so on allocates memory space for the object.