What are the "these" you speak of?
Explanation:
my answer is the third one
There's many answers for this question, as long as it's a similar word to disbelief. President Roosevelt's reaction was pretty much thinking, "This is unbelievable." So therefore, you can put disbelief or distrust.
The Answer is Rocky Mountains
The United States first began developing nuclear weapons in 1939, during World War II, under the order of President Franklin Roosevelt. Motivation was the fear that US was engaged in a race with Nazi Germany to develop nuclear weapon. This project is best known as Manhattan Project.