I think you forgot to include the options. But to help you, the countries that are part of the heavily industrialized Black Triangle of Eastern Europe are Poland, Germany, and Czech Republic. Thank you for posting your question. I hope this answer helped you.
Here you go
I highlighted where all the info is
Answer:
in 1846, a dispute over the border between Texas and Mexico resulted in armed conflict, and the Mexican–American War began. After offering to buy the territory, Polk moved U.S. troops into a place that Mexico said was not in Texas, but rather part of the Mexican state of Coahuila. The Mexican army attacked them.
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