I believe the answer is B. Germans, since we're talking about Oklahoma.
Answer:
The correct answer is B. The group of immigrants that made up the largest ethnic bloc in Oklahoma at statehood were Germans.
Explanation:
70% of the population of the state of Oklahoma is classified as white. Of this, most, as in the rest of the country, is descendant of German immigrants who arrived in the United States in the late 1800s. In 1907, the year of statehood, German Americans made up 20% of the state's population.