Your content_script isn't calling the correct method to send the response. Your listener function is naming it callback but then trying to use sendRequest . You should also either remove the function name or define it outside of the addListener for clarity.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.