In which story is the technical element more believable; or, to put it another way, less unbelievable?

Write an essay containing the following elements.

To what extent does technology motivate each story? Without the SF mainstay of futuristic machines and gadgets, would the stories work at all? Why or why not?
In which story is the technical element more believable; or, to put it another way, less unbelievable?
Technology can be fascinating, but without people, there’s no story. Which story presents the human element best? What is it, that makes the presentation of the human element in that story particularly effective?
In conclusion, which story did you find to be the most entertaining? The most memorable? Why?
Be sure to use appropriate citations and references.