If you couldn't guess, the third possibility is the most plausible
given the data that has been collected. In our past, aliens' existence almost became common knowledge, due to mistakes on
their part and some of our own.When a UFO crashed outside Rosewell, and was recovered by the military, their presence in our lives was broadcast around
the world, only to be covered up the very next day by our government.
It was clear that our rulers didn't want us to find out the truth
about our presence in the universe and of alien life, so they thought it better to collaborate with the visitors, gain technology,
and keep their existence a secret.
This plan has worked for most of our past, except for the fact that the aliens
have their own agenda , are seeking acceptance in our culture. The human
race is being changed, slowly, even if it is one person at a time.
People are being abducted, tested, and altered genetically to allow
for other portions of their brains, which control esp, telepathy, etc; to become active. In doing so, the human species will
be able to interact on a new higher level of consciousness, see the futile practices of worshipping gods and fighting wars.
Along with direct manipulation of the human species, hybrids, crosses
of aliens and humans are being made, so that they will be able to live amongst us without our knowing.
If the aliens were hostile, and wanted our planet for its resources, they would
have taken it away from us centuries ago when we still thought the earth was the center of the universe, not now when we have
nuclear weapons, lasers, and space crafts of our own.