The "German Triangle" in the Mid-Nineteenth Century Referred to

The "German triangle" in the mid-nineteenth century referred to

A) a Baltimore neighborhood with a large German immigrant population.
B) the identifying patch German immigrants were forced to wear in some American cities.
C) Cincinnati, St. Louis, and Milwaukee-cities with large German populations.
D) the special kind of ballot Democrats gave German-speaking voters.
E) the superior plow that German immigrant Thomas Mannheim introduced to the United States.