Final answer:
The words 'striking,' 'weapons,' and 'formidable' suggest that John Carter recognizes the creatures as noticeably threatening, making option B the correct answer.
Step-by-step explanation:
The words striking, weapons, and formidable within the context of the passage help to convey John Carter's impression of the creatures as being highly noticeable (striking) and potentially dangerous (formidable). The use of the word weapons in reference to the creatures' tusks underlines their capability to inflict harm, thereby indicating that John Carter perceives them as threatening.
Given these descriptions, the correct answer to the question regarding John Carter's impression would be option B: They indicate that John Carter is well aware that the creatures could be dangerous. This is appropriately inferred from the descriptors used, which highlight the prominence and danger of the creatures' natural armaments without suggesting aggression or delight on Carter's part.