What were some tactics used to decrease the number of Nazi U-boat (submarine) attacks off the North Carolina coast?

Question 4 options:

Supply ships were completely banned from the North Carolina coast.

American submarines began patrolling the area and torpedoing the U-boats.

Airplanes were used to spot U-boats, so they could be avoided or destroyed.

A blackout along the coast made it more difficult for the U-boats to target ships.

Pick the answers more than one answer that goes with that question

Banning Coast lights and airplanes were used to spot U-Boats

Explanation:

British experience in the first two years of World War II, which included the massive losses incurred to their shipping during the "First Happy Time" confirmed that ships sailing in convoy — with or without escort – were far safer than ships sailing alone. The British recommended that merchant ships should avoid obvious standard routes wherever possible; navigational markers, lighthouses, and other aids to the enemy should be removed, and a strict coastal blackout be enforced. In addition, any available air and sea forces should perform daylight patrols to restrict the U-boats' flexibility.

an expansion is one of two basic business cycle phases; the other is contraction. the transition from expansion to contraction is a peak, and the changeover from contraction to expansion is a trough.

i believe the answer is c