Some space experts point out that space stations and probes are likely to bring back space microbes, which may have mutated and deformed in isolated space, and if they return to Earth and escape the fate of being destroyed, they will definitely pose a threat to humanity. It is reported that the Mir space station was once full of various mutant fungi. If they are mixed with the metal, glass and plastic bacteria that can be decomposed in the earth's soil, it is enough to pose a lethal threat to humans. What is the correct understanding of this article? ["The Earth's environment is under threat from space mutant fungi.", 'Human space activities may cause space microbes to reach Earth.', 'With the increase of human space activities, space trash has affected human life.', 'Space variant fungi will be the deadliest threat to humans.']