Thanks for playing the Tuesday Brain Game. In the following graphic, each of the 26 letters of the alphabet has been grouped into one of five rows. Can you identify the criterion that was used to place these letters into these groups? Good luck!

Here is the 

THE SOLUTION:

The letters are grouped by the number of single "line ends" that each has.

The first row's letters have no line ends;
the second row's letter has one line end;
the third row's letters have two line ends;
the fourth row's letters have three line ends;
and the fifth row's letters have four line ends.