Hint: The atomic bomb dropped on Hiroshima in Japan on 6th August 1945 was an attempt made by the United States of America. It was during the end of World war II and believed that in order to put an end to the war the bomb was dropped.
Complete answer: On August 6, 1945, the United States of America was the first country and the only nation that used an atomic weapon or Nuclear weapon during the time of World war II. The war in Europe had come to an end when Germany surrendered on 8 march 1945 but the war continued in the Pacific between allies and Japan. The Allied powers wanted Japan to surrender however the ultimatum was ignored by Japan which led to the continuation of the war and then finally the US developed Nuclear weapons, tested them and dropped the atomic bombs on the two cities of Japan, Hiroshima and Nagasaki. The bomb that was dropped on Hiroshima was named the little boy.
-On 9th August 1945 another nuclear bomb was dropped on the city of Nagasaki by the United States of America which was named fat man.
Hence there were two nuclear bombs used to end World War II by the United States of America, little boy and fat man. While the fat boy and little man are false because there were no bombs with such names.
Therefore, the correct answer is B.
Note: The consequences of the bombings took around 90000 to 146000 people lives. The two cities were devastated. Even after months of bombings, many people continued to die because of the radiations of the bombs, burns and other wounds. Malnutrition and illness were other problems. The bombings on the Japanese States led the beginning of the new era in world history known as the cold war between the US and USSR.