Answer:
A
Explanation:
Look at each of the answer choices:
A) This describes the habitats of the narwhals, but instead of giving a concrete picture of exactly where these animals live, the statement simply says that it's "dark for one half of the year, covered in ice for the other half of the year". This lends a sort of mysterious vibe to the habitat of the narwhal, making this a very good candidate for the right answer.
Choices B, C, and D all include certain specific scientific facts that create a sense of truth around narwhals, eliminating the mystical atmosphere that choice A provides.
Thus, the answer is A.
