IQ Brain Teaser #178

What is the maximum number of straight lines you can draw between 9 evenly spaced dots in a 3x3 grid (like the one shown below) without lifting your pencil and without retracing any lines? Any line connecting two dots counts as one individual line. Use only horizontal and vertical lines. In the example below, 6 lines have been formed. But what is the maximum number possible? 7 8 9 10 11 12 13 14 15 None of the above view results