Use the map to answer the question.
A map of Texas shows several Underground Railroad routes from surrounding states heading south and southwest through Texas toward Mexico and the Gulf of Mexico. The map key shows Underground Railroad routes in dashed lines. Current state boundaries are shown with solid lines. Cities are marked with a dot. An Underground Railroad route begins in Arkansas in an area with unlabeled converging rivers, crosses the border into present day Oklahoma, then heads south across the Red River into Texas. The route passes through Dallas, crosses the Brazos River and the Colorado River, passes through Austin, and continues to San Antonio. The route splits at San Antonio. One route continues west toward the city of Piedras Negras, and the other route continues south toward Laredo on the Rio Grande. A second route from Arkansas heads south through the northwest corner of Louisiana, crosses the Red River, passes through Nacogdoches, crosses the Brazos River, and joins the first route at Austin. A third route begins in northwest Louisiana, crosses into Texas, passes through Nacogdoches, and continues to Houston. The route crosses the Brazos River and the Colorado River and passes through the city of Brazoria, where it splits. One route continues to the Gulf of Mexico. The other route continues south along the coast of the Gulf of Mexico to the city of Matamoros. A fourth route begins in south central Louisiana, crosses into Texas, connects with the other route through Houston, heads south to the city of Galveston, and continues to the Gulf of Mexico. A scale shows 100 miles and 100 kilometers.
Based on the map, what geographic feature would escaping enslaved people need to cross to gain their freedom on the Underground Railroad?(1 point)
Responses
the Colorado River
the Colorado River
the Red River
the Red River
the Brazos River
the Brazos River
the Rio Grande