Answer: D. That England's guard was down and England wasn't ready for an enemy attack.
At the beginning of The War of the Worlds, Wells argues that when the Martians arrived, England was unprepared for their attack. He explains that people did not bother to think about other planets. Moreover, those who did think about the universe believed humans to be the only intelligent species. Wells argues that it was human arrogance that led them to be so unprepared for an attack.