What was one major cause of worldwide conflict during the first decade of the 21st century? A. clashes between groups with different religious or political beliefs
B. struggles between intergovernmental organizations from different regions
C. competition between countries for leadership over the united nations
D. disagreements between leaders over how to properly address terrorism

Correct answer is A. clashes between groups with different religious or political beliefs.

Explanation:

Option A is correct, as with the rise of Islamic fundamentalism at the beginning of 21st Century the conflict arose, especially in the area of Middle East.

B is not correct as there were no such conflicts at the time.

C is not correct as UN has a mutual role to preserve peace in the world, and internal conflicts are not usual in it.

D is not correct as leaders were addressing terrorism in the same manner.

tearing down the berlin wall.