This question involves graph theory

[10 pts] Imagine a country that has n E N cities that are linked by highways, where a highway (which can be traversed in either direction) links exactly two cities and the only way to enter or exit a city is via highway(s). The president of this country hates wastefulness, so she ensured that for any pair of cities in the country, there exists only one set of highway(s) linking the two cities. Finally, suppose that there exists at least one city in this country such that there exist d E N distinct highways via which you can enter or exit the city. Prove that there are at least d cities such that there exists only one highway Via which you can enter or exit the city