The "dark forest theory" proposed in the science fiction "Three-Body" tells us that humans must not reveal the location of our earth to the universe, or they will be destroyed by an alien civilization. However, as early as the "Three-Body" publication in 1974 In the year, humans sent a radio signal to the Wuxian cluster, which is more than 22,000 light-years away from the earth, and proactively announced its existence to the universe at the speed of light. This M13 cluster of Wuxian stars has hundreds of thousands of stars. Scientists believe that stars are usually accompanied by planets, but there can be no life on the stars, but there may be on the planets. People who believe in the dark forest theory can't help worrying about the reckless behavior of humans, and think that the good expectations of humans may be Usher in cruel reality. Which of the following, if true, best illustrates this need? ['So far, humans have not found any signs of alien life.', 'Earth-like planets are not uncommon, with an average of 1 every 5 stars.', 'There are no planetary systems in the densely packed Star cluster of the Perseus.', 'Even if the civilization of the Mars cluster is received, it will be after 22,000 years.']