"Dr. Lawrence Nixon" successfully challenged the "white primary" law in Texas that prevented African Americans from voting in the Texas Democratic primary.
Option: B
Step-by-step explanation:
A black doctor in El Paso, Texas and a Democratic Party candidate named as Dr. Lawrence A. Nixon, tried to vote in the 1924 Democratic Party primary in El Paso. He claimed that the legislation was in violation of the Fourteenth and Fifteenth Constitutional Amendments.
Nixon v. Herndon was a U.S. Supreme Court decision that overthrew a Texas law of 1923 banning black people from voting in the official Texas Democratic Party. It was effectively the only competitive method and ability to select candidates for the Senate, House of Representatives and State offices because of the limited number of Republican Party operation in Texas at the time regarding the suppression of black voting by poll taxes.