Consider the LinkedIntList class. When isEmpty is true, which of these expressions are both

meaningful AND true?

$($by "meaningful" we mean that the code doesn't cause a NullPointerException$)$

head $!=$ tail

tail.element $==$ null

tail $==$ null

size $=0$

head.element $==$ null

head.next $==$ null

tail.next $==$ null

head $==$ null