Considering the data presented in the question, the statement that best explains the political pattern shown in the table is "The devolution of Yugoslavia occurred primarily along national lines, resulting in countries with a defined ethnic majority."
This is because from the table, it is observed that each country formed out of Yugoslavia has the highest or majority ethnic group that formed the country's name.
For example, Croatia has the highest Croat ethnic group, Serbia has the highest Serbian ethnic group, Slovenia has the highest Slovene ethnic group.
Hence, in this case, it is concluded that the correct answer is option A.
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