Adding five of the six fractions $$\frac{1}{2}$$, $$\frac{2}{3}$$, $$\frac{1}{4}$$, $$\frac{1}{6}$$, $$\frac{1}{9}$$ and $$\frac{1}{18}$$ gives a total of $$1.5$$.  Which of the fractions is not used? 
选项为:A:$$\frac{1}{3}$$  B:$$\frac{1}{4}$$  C:$$\frac{1}{6}$$  D:$$\frac{1}{9}$$  E:$$\frac{1}{18}$$  请回答其中一个选项.