Read the adapted excerpt from Moby Dck by Herman Melville about a giant white whale known as Moby Dck. Aside from those more obvious considerations touching Moby Dck, which could not but occasionally awaken in any man’s soul some alarm, there was another thought, or rather vague, nameless horror about the whale, which at times by its intensity completely overpowered all the rest; and yet so mystical and well nigh ineffable was it, that I almost despair of putting it in a comprehensible form. It was the whiteness of the whale that above all things appalled me. But how can I hope to explain myself here; and yet, in some dim, random way, explain myself I must, else all these chapters might be naught.

Which sentence best identifies the main idea for a summary of the excerpt?

A.
The narrator is amazed at the power and intensity of the whale.
B.
The narrator considers the whale, Moby Dck, to be mystical.
C.
The narrator is most alarmed by the white color of the whale.
D.
The narrator tries to explain the horror of encountering the whale.