Farmer Dunphy has $$16$$ metres of fencing.  He wants to make a closed rectangular pen.  He uses a long wall for one of the sides.  Each side of the pen is a whole number in metres.  What is the largest area that the pen can be? 
选项为:A:$$25\text{m}^{2}$$  B:$$27\text{m}^{2}$$  C:$$30\text{m}^{2}$$  D:$$28\text{m}^{2}$$  E:$$32\text{m}^{2}$$  请回答其中一个选项.