Tiantian drank $$6\frac{3}{8}$$ litres of water. Matthew drank $$4\frac{5}{6}$$ litres of water. How many litres of water did the both of them drink altogether? Give your answer as a mixed number in the simplest form. 
选项为:A:$$10\frac{4}{7}\ell$$  B:$$10\frac{5}{8}\ell$$  C:$$10\frac{15}{24}\ell$$  D:$$11\frac{5}{24}\ell$$  请回答其中一个选项.