Which of the Following Is Not Considered a Likely Solution

Multiple Choice

Which of the following is not considered a likely solution to the question of why we are not currently aware of a galactic civilization?

A) There is no galactic civilization because civilizations are not common.
B) There is no galactic civilization because civilizations do not leave their home worlds.
C) The galactic civilization is deliberately avoiding contact with us.
D) The galactic civilization probably is undetectable to us because it makes use of technologies that do not obey the known laws of physics.
E) There is no galactic civilization because most civilizations destroy themselves before achieving interstellar travel.