Final answer:
Navy watches are divided into day and night categories to maintain continuous ship operations around the clock, with day watches covering daytime hours and night watches covering nighttime hours.
Step-by-step explanation:
The question asks about the two major categories into which navy watches are divided. The correct answer to the question is B. Day and Night. Watches in the navy are traditionally split into two broad categories: day watches and night watches. This system is designed to ensure that the ship's operations continue uninterrupted 24/7. Day watches typically run from the morning until the evening, and night watches cover the hours from the evening until the morning.