During the Civil War, the Union's Attempts to Cut the Confederacy

During the Civil War, the Union's attempts to cut the Confederacy off from seaborne commerce proved difficult at first because:

A) British merchant ships aggressively pushed through to southern ports and challenged the Union's authority to block their trade.
B) Confederates relied on allied coastal tribes to harass the Union navy with small attacks from the shore.
C) the strategy of a naval blockade was new and had never been tried before.
D) the Union only had forty-two ships to patrol 3,550 miles of Confederate coastline.
E) the southerners did not need foreign imports and ignored the Union occupation of New Orleans.