Xplain how rockefeller gained and controlled the oil industry?

Which of the following is an example of nationalism? a. a leader calls on his country's allies to protect his country from a threat posed by a neighboring nation-state. b. one country declares war on another power after that power invades the first country's ally. c. an activist organizes a protest of ethnic minorities in a country to demand that they be given their own country. d. under an alliance, one country promises to defend another country from an attack by a third.