In the following passage some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

For better or for worse, we are living in a _____ which is based physically on western science and technology. This has _____ consequences for the scientist. Initially he was an _____ force in the unfolding of human _____. This he can no longer be. As Neils Bohr has said, scientists must become _____ of the fact that they are not merely observers, but also actors on the stage of life.