$$a=\left( -\frac{1}{6} \right)+\left( -\frac{1}{5} \right)-\left( -\frac{1}{4} \right)$$．则$$a$$的相反数是．
选项为:A:$$-\frac{17}{60}$$  B:$$-\frac{7}{60}$$  C:$$\frac{17}{60}$$  D:$$\frac{7}{60}$$  请回答其中一个选项.