Dumbfounded means to be left utterly speechless, or to simply be amazed/confused.
I think the correct answer is A I am currently reading Romeo and Juliet!
Answer: A. George Stephenson was joined by other inventors to enhance the design of locomotives.
Explanation: I got it right on Edmentum.
Confort zone refers to the brunch of situations at which a specific individual feels comfortable. He/She knows perfectly how to act and react in that environment and it does not suppose a challenge to perform properly in these situations.
On the contrary, when someome steps out of the comfort zone starts to feel vulnerable, hesitates and needs to think many times about the next step in the path. But for many, like the users of the sentence "''life begins at the end of your comfort zone'' feeling the risk and achieving to overcome, is actually what makes you feel alive.
