Answer: A. was the largest seaborne expedition before World War II.
Step-by-step explanation:
The Mongolian Navy was regarded as of the largest in the world, especially during Kublai Khan's time.
It should be noted that majority of the fleet sank when Mongol invaded Japan. Later in the 1930s, there was a recreation of the Mongolian Navy by the Society Union.
Therefore, the correct option will be A.