What new aspect of combat during the world war i is described?
a) guerilla warfare
b) nuclear weaponry
c) biological weapons
d) trench warfare

Well without a description om shooting in the dark. But id assume that the answer is Trench Warfare. Since A- was around since contact with Native Americans and largely popular in North America. B- Only was used and discovered in WW2. And C- was used but was largely frowned upon and condemned by both sides.