State whether each of the following are true or false. If false, give an example of a string that is in the language of one regular expression but not the other. If true, explain why. (a) (ab) and ab (b) (a b)c and ac bc (c) (ab) and (a b) (d) AB and BA where A and B are arbitrary regular expressions. (e) AA and A where A is an arbitrary regular expression. (f) A and (AA) where A is an arbitrary regular expression.