What does static mean in Java?

$($a$).$ Its value can never be changed.

$($b$)$ It always requires a reference to be called.

$($c$)$ Each instance of the class has its own copy of the attribute$/$met$.$

$($d$)$ There is only a single copy of the attribute$/$method outside instances of the class.

$($e$)$ There can be only one.