How many privat blockade runners were in the union blockade in 1861?

During the war,  some 1,500 blockade runners were captured or destroyed using only 500 ships
The blockade runners were relying mainly on the British Steam with higher than average speed.The union prefers to move their boats at night because it's undetectable by the enemy.

The blockade runners were steam ships that were used to break the Union blockage along the Atlantic and Gulf of Mexico. There were an estimated 1,455 blockade runners. The Union Navy captured over 1,100 blackade runners and destroyed another 355 vessels.

Ithink the answer is c