Countries encouraged nationalism leading up to World War I by asking citizens to burn crops in their own country to keep food from the enemy.

cooperate with other countries to prevent conflict.

buy products from other countries to boost the economy.

support their own country in times of need or conflict.

to answer this question you need to explain more

b) race riots in several cities

herodotus taught this. herodotus was an ancient greek historian who was born in halicarnassus in the persian empire. he is known for having written the book the histories, a detailed record of his "inquiry" on the origins of the greco-persian wars.

on my last question