There are 4 zones of 3 towns each.
In a zone there are 3 towns.
Each town connects with the other town in 3 lines.
Hence total number of lines is 3* 3 = 9.
4 zones have 9*4 = 36 direct links within it.
Now,
Consider a town in Zone 1. There are 9 towns outside this zone.
Hence 9 lines are required to connect between this town and the other 9 towns.
Similarly, there are 12 towns, each with 9 towns outside its own zone.
So, totally, there will be 9*$\frac{12}{2}$ = 9* 6 = 54 lines inter zone
So, the total number of lines will be 36 (within zone) + 54 ( inter zone) = 90.
Hence Option (B)90 is the Answer.