 Which is the best deccription of why the humans are feared by other alien races?
If they carried out the threats of their present attitude, Earth would have to send Marshall to replace him. What I meant was that I expected someone from Earth to break through our blockade and come here. "If you wanted someone from Earth to come here to see you, why did you put the cordon around Earth? And why did you drop a planet-buster in the Pacific Ocean, and tell us that it was triggered to go off if we tried to use the distorter drive? But you did come, so I can tell you that although I am the leader of one of the mightiest peoples in the Galaxy, whereas there are scarcely six billions of you squatting on one minor planet, we still need each other. "You upstart Earthlings are a strange and a frightening race," he said. There was even serious discussion of destroying Earth out of hand, while it is still possible. While these creatures could by no means be classed among the intelligent races, there was a general expectation, which we reported to the Sunda, that they would some day come to be numbered among the Servants of the Emperor. They had quickly located a dozen planets, and one that looked enough like Earth to be its twin sister. They had headed for that planet confidently and unsuspectingly, using the ion drive. Two weeks later, while they were still several planetary diameters from their destination, they had been shocked to find more than two score alien ships of space closing in on them—ships that were swifter and more maneuverable than their own.
 Their technology and ideas develop at a rapid pace
 Their technology and ideas develop at a rapid pace  They are known to wipe out alien races with their time travel technology  They have superior strategies to get past any race's defense system  They have control of large amounts of bombs that can be used to destroy planets