What led to higher casualty numbers and a prolonged war during WWI?

Answer:
B.) New Weapons and Technology is the correct answer
Explanation:
By the time of the armistice on November 11, 1918, the use of chemical weapons such as chlorine, phosgene, and mustard gas had resulted in more than 1.3 million casualties and approximately 90 000 deaths.
Answer: I'm pretty sure the answer is B. New weapons and technology
Explanation: