Answer:
Option D.
Step-by-step explanation:
Both battles had high casualties without either side winning an advantage, is the right answer.
The Battle of Verdun which took place in the period between 21st February to 18th December 1916 was the longest of all battles during the First World War.
Another important battle of the First World War that took place between Germany and France with its allies Britain, was known as the Battle of the Somme. In both of these battles both the sides causes heavy casualties without either side accomplishing an advantage. Therefore, option D will be the right answer.