Respuesta :
The second sentence in the excerpt from the "The Time Machine" suggests that the time traveler was wrong in his assumptions about the future. The destruction of the earth was shown in that sentence. The behavior of the people at the future time indicates he was mistaken.
I believe the correct answer is "It was natural on that golden evening that I should jump at the idea of a social paradise." Due to it being the only sentence that implies he was wrong. By saying he "I should jump" implies that he assumed but the reality was not the same.