The pope in Rome and the patriarch in Constantinople argued about the treatment of heretics.
having icons in the church.
the language for church services.
the holy text

B, having icons in the church

I know this because I took a test with this same question!

This dispute was one of the many reasons that lead to a split between the 2, but it was also the root cause of the Iconoclast Controversy.

Hope this helps! :)

this is a good question! i'll do some research and come back when i have the answer!

nations must cooperate to bring about and maintain world peace.

nations must not wage wars or commit war crimes in a desire to control other nations.

i think i know which options you have but if these aren't options let me know