Question

consider the following research topic:
subway systems around the world
which book would likely include the most relevant information about this topic?
under the sea: are underwater subways the future of world travel?
a green commute: the need for climate-friendly public transportation systems
underground travel: the globes most famous subways

Explanation:

The research topic focuses on global subway systems. The first book only covers underwater subways (a narrow subset), the second focuses on climate-friendly public transit broadly, while the third directly centers on famous global subways, matching the topic.

Answer:

Underground Travel: The Globe's Most Famous Subways