The table below illustrates a self-organising map of size 4 by 4 with 1 weight per processing unit. Given an instance with a value of 2, what column contains the best matching unit?

     1      2     3      4

1   1.2   1.4   2.4   3.0

2   1.4   2.2   2.6   3.2

3   1.8   2.7   2.6   3.4

4   2.0   2.8   2.8   3.5