Which of the following statements is correct?
A.
User variables exist only for the duration of the connection in which they are created.
B.
User variables are always persistent from one connection to the next, provided the user is the same.
C.
User variables persist from one connection to the next, regardless of user.
D.
User variables persist from one connection to the next provided the user is the same and the persistent keyword is given to the set command at definition time.