The correct answer is option 1: The fission bomb dropped at Hiroshima.

The term "Little Boy" refers to the atomic bomb that was dropped on the city of Hiroshima, Japan during World War II. It was the first atomic bomb ever used in warfare. `Little Boy` was a uranium-based fission bomb, which means it caused a nuclear chain reaction by splitting atoms. This release of energy resulted in a devastating explosion that destroyed the city and caused immense loss of life. The use of `Little Boy` by the United States marked a turning point in history, as it demonstrated the destructive power of nuclear weapons and led to a new era of warfare. It ultimately played a significant role in Japan`s surrender and the end of World War II. It is important to note that `Little Boy` should not be confused with the bomb dropped on Nagasaki, which was a different type of atomic bomb called `Fat Man`, option 2.