Even though the devastation caused by the atomic bomb was tremendous, and had killed hundreds of thousands of Japanese citizens, the Emperor refused to back down. Surrender in the Japanese culture is shunned very harshly as it made one cowardly.
What do these numbers mean I don’t exactly understand the question
C is the correct answer. Parliamentary allows the leader to enforce and enact laws without involvement from legislative board. President system however requires approval from Legislative and Judicial senate and/of House of Representatives
Massive retaliation means the US would respond to an attack with a larger response to annihilate the enemy.
Massive retaliation required a bigger, stronger weapon than held by an enemy. This policy forced an intense arms race which required the US to win in order to execute the plan. The use spent millions developing nuclear weapons and eventually the space program to prove they were prepared for an attack by the USSR.
I think you may need to finish the rest of this question, or rephrase it, I'm happy to help either way.