For each of the following sets, write down all the elements of the set.
(a) A is the set of even numbers between 3 and 17.
(b) B is the set of natural numbers less than 10.
(c) C is the set of common factors of 21 and 28.
(d) D is the set of multiples of 4 that are less than 30.
(e) E is the set of vowels in the word Griffithdore.