Which idea is BEST supported by the last
paragraph of the passage, on pages 5 and 6?
Humans may not have come under threat if they
had made an effort to communicate with other
planets.
If Martians had invaded in an earlier era, humans
would have been better prepared.
If Martians had been more careful in their planning,
they could have staged a more successful
invasion.
The impending events could have been prevented
if humans were more advanced in their learning.