Answer:
C. The ordinal level of measurement
Step-by-step explanation:
The ordinal level of measurement is most appropiate because years in which a war was started can be ordered, besides, these years are only labels because it is not reasoble to do opperations with these numbers, it is something similar to have postal codes (which are nominal data), but in this case we can order the years, for instance, 1900 < 1945, etc. The interval level and the ratio level of measurement are not appropiate.