To automatically open the console when a JavaScript error occurs which of the following is added to prefs.js? | Java Script

A.  user_pref(" javascript.console.open_on_error", false);
B.   user_pref("javascript.console.open_error ", true);
C.  user_pref("javascript.console.open_error ", false);
D.   user_pref("javascript.console.open_on_error", true);

Ans: D