How do you make someone brainliest

Arguably one of the most important inventions of the 20th century was a) the transistor. b) air conditioning. c) the vacuum cleaner. d) radio broadcasting.

Why was mao zedong’s communist china ready to use military tactics against the troops of us general douglas macarthur in korea? a. mao zedong had long planned to declare war against the united states. b. us troops kept marching farther into north korea, getting closer to the chinese border. c. us president harry truman threatened to use nuclear weapons against china. d. kim il sung had requested china’s to declare war against the united states.

What was one major cause of worldwide conflict during the first decade of the 21st century?