D or A is the answer. I least I narrowed it down.
Answer: The strength, maneuverability and speed of the longship gave the Vikings vital key advantages. The choice between sail and oars allowed the Norse warriors to row until land was sighted and then proceed silently, under sail, during the night or in the early morning. This gave their attacks the element of surprise.
Explanation:
A French alliance helped the US win the Battle of Saratoga