27. fire stations, roads, sewers, and bridges are examples of
a. open spaces.
c. urbanization.
b. infrastructure,
d. wilderness.

b. Infrastructure  

Explanation:

Infrastructure is the fundamental facilities and necessary for the economy of a region to function.

It is composed of improvements such as fire stations, roads, sewers, and bridges, and many others, like railways, tunnels, water and electrical supply, and communications.

An example of infrastructure is the Samuel de Champlain Bridge (below), which crosses the St. Lawrence River from Montreal en route to the United States. The bridge it replaced carried about sixty million vehicles per year, more than $20 billion in cross-border trade and was crucial to the economy of Montreal and for Canada as a whole. The new bridge has even greater capabilities.

a. and d. are wrong. Open spaces and wilderness require infrastructure, but they are not infrastructure.

c. is wrong. Urbanization refers to a population shift from rural to urban areas