Final answer:
The narwhal is best known for its tusk because of its historical use in cultural artifacts and the rarity and unique appearance of the tusk, which have become symbols of wonder in various cultures.
Step-by-step explanation:
The detail that best supports the author's claim that the narwhal is best known for its tusk is the use of the narwhal's tusk in cultural artifacts, such as carvings, which are often highly valued and recognized. This is evidenced by various historical accounts and cultural practices that involve using ivory from tusks.
Which are not just limited to elephants and walruses but also include the distinctive tusk of the narwhal. For example, the Aleut were known for carving walrus ivory, and the tradition of using ivory for art and utilitarian objects spans across different cultures and periods, implying the value of such materials, which includes narwhal tusks.
Another aspect of the narwhal's fame is the rarity and intriguing appearance of its tusk, which has captured human imagination. The narwhal's tusk is not just a material resource; it stands as a symbol of wonder and has piqued human interest, thereby reinforcing the narwhal's recognition mainly for this characteristic.