First scientist to conduct a controlled nuclear chain reaction experiment

Who was the first scientist to conduct a controlled nuclear chain reaction experiment? 

1. Arthur Holly Compton

2. Enrico Fermi

3. Richard P. Feynman

4. Albert Einstein

Correct Option: Option B,

Enrico Fermi

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Enrico Fermi (29 September 1901 - 28 November 1954) was an Italian  physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and the "architect of the atomic bomb".