Edge set consists of edges from i to j, using either two conditions are j = i + 1 or j = 3i
Second choice helps us to move from 1 to 100. The trick to slot this is to think the other way
around. Try to find a 100 to 1 trail, instead of having a 1 trail to 100.
So, the edge sequence with the minimum number of edges is
1 → 3 → 9 → 10 → 11 → 33 → 99 → 100
which consists of 7 edges.
Hence the correct answer is 7.