3. How did a barrio develop in Los
Angeles during the 1920s?

Barrio develop in Los Angels as result of influx of Mexicans who took up jobs thereby increasing the growth.

Explanation:

Barrio is a small city in Los  Angels concentrated with Spanish speaking people who are more popular in the area during the 1920s era. The Mexicans were leaving there country for better way of life and moving to Barrio in Los Angeles to take up the available jobs which in return speed up the rate of development that took place there.

a, he promoted disarmament