2007 AMC 8 Problems/Problem 16
Go here for the diagram: Media:http://www.artofproblemsolving.com/Wiki/index.php/File:AMC8_2007_16.png
The answer is A If you look at the diagrams, you can see the center in A where the points are at 1,1 2,2 3,3, etc. Thus, its's the answer.