Answer:
Prince Henry the Navigator
During the prohibition in the United States illegal saloons were called speakeasies. They were called this because they were often located in an attic or basement were you needed to whisper a password or speak easy and you needed to stay quiet while inside.
Currently studying this right now and I am fairly confident it is A.
“By then knowing how to measure the circumference of the earth”
Because of World War II and the New Deal