What was a characteristic of the Naval Reserve between World War I and World War II?

The characteristic of the Naval Reserve between World War I and World War II was that there were no ready reserve units or reserve officers on extended duty. During this period, the concept of the naval reserve was not as developed as it would become later. The focus was primarily on expanding the active-duty navy to meet wartime demands, and the structure of the reserves typically did not include ready units that could be mobilized quickly in times of crises.

This lack of ready reserve units or extended duty officers meant that while reservists were available, they were not in a state of preparedness that would allow for immediate deployment or operational readiness as seen in later conflicts. Over time, the understanding of the role of the reserves evolved, leading to changes in how reservists would be trained and mobilized.

In contrast, the other options describe situations that were not characteristic of the Navy's reserve structure during the stated timeframe. For example, the establishment of numerous ready reserve units and an emphasis on operational training were more prominently addressed after World War II as the military restructured to better utilize reserve forces.