A string $$12$$ meters long is cut into $$6$$ pieces of equal length.  What is the sum of the lengths of any $$4$$ of these pieces? 
选项为:A:$$2\text{m}$$  B:$$4\text{m}$$  C:$$6\text{m}$$  D:$$8\text{m}$$  请回答其中一个选项.