Given the code fragment: 

Which method should be used on line 3 to enable default validation mechanism? 

Answer options:

A. u.setProperty(String, Object)
B. u.setProperty(Schema)
C. u.setEventHandler(ValidationEventHandler)
D. u.setAdapter(XmlAdapter)

D

Reference: https://docs.oracle.com/javaee/6/api/javax/xml/bind/Unmarshaller.html