In a small town a bank (b), school (s), town hall (t), and shopping mall (m) are connected by a series of narrow one-way streets; a street from the town hall to the bank, one from the bank to the school, one from the school to the shopping mall, and one from the shopping mall to the town hall.
Assuming that the given streets cannot be widened, assist the mayor in planning the construction of new roads to increase traffic flow. Assume that if there is a one-way street from point a to b and one from point b to c, there should be one from point a to c.
Explain why your solution (1) is the only option to satisfy the condition of (1).