They are easier to carry.
They can be used for navigation within a city.
Tourism is the LARGEST industry in the world.
The best bibliogaphic entry would probably be: Smythe, Clark. <em>Unsinkable: Folly on the Titanic</em> Little, Brown: New York, 1976.
That is because it seems to be a book about the Titanic itself, whereas the other ones have to do with:
- topics which are less directly related to the subject-matter (the first entry is about maritime laws and the third one is about the animal and plant populations of the lands near the North Pole),
- personal, relative accounts of the events (like the fourth entry, which is an autobiography of a survivor and therefore describes the wreck through the character's own perspective) as opposed to more factual material.
The soil layers are, in order: dirt, humus, rock. So the answer is D.
