I'm not sure 100% what exactly this question is asking, but I know World War 1 was the first war to include Gas masks and Chemical warfare, so that is more than likely the answer.
Answer:
Gold had not been discovered there yet, but Polk wanted California and its magnificent San Francisco Bay as the American gateway to trade with China and other Asian nations. Polk was worried that other nations, such as England or France, might take California if the United States did not act.
Explanation:
The answer to this statement is B
The main reason that New Mexico faced such difficulty in becoming a state in the 1800s was because Congress was unwilling to accept New Mexico's application for statehood. People were suspicious of the area's inhabitants and their varying background.
