Which statements about Preferences are true?

Question $21$Select one or more:

a$.$

Preferences are best saved in a file in the user$$s home directory.

b$.$

Preferences represent a snapshot of a program saved between sessions.

c$.$

To handle preferences, Java provides a class Preferences in the java.util.prefs package.

d$.$

Every time the program starts up$,$ it reads the preferences, if any are available. Every time the program terminates, it saves the preferences.