Set C consists of all of the positive integer multiples of 5 that are less than 20. Set D consists of all of the factors of 20. Which of the following is the union of Set C and Set D ?
(A)\(\lbrace 1, 2, 4, 5, 10, 15, 20\rbrace\) (B)\(\lbrace 2, 4, 5, 10, 15\rbrace\) (C)\(\lbrace 5, 10\rbrace\) (D)\(\lbrace 5, 10, 15, 20\rbrace\) (E)\(\lbrace 2, 4, 5, 10\rbrace\)
A