The correct option is A 1
The numbers adjacent to 2 are 1,4,5.6. Therefore, number opposite to 2 is 3.
Number adjacent to 2 are 1 and 5 and 6 and 4 .Therefore, from the above figure 5 and 4 are opposites.
Therefore, 1 and 6 are opposite to each other.
Hence the correct answer is Option A.