Answer:
We don't know for sure, but we want to believe.
Step-by-step explanation:
Outer space is a vast expanse that we have so much more to learn about, which is why it's hard to flat-out deny the possibility that other intelligent lifeforms exist. New species are continually being discovered in the ocean, and some animals thought to be long gone have emerged from the thick cover of jungles and the deep sea to be rediscovered.