Question

what is the shift from mechanistic view to a holistic and exological view of the world​

Answer 1

This question is from the chapter The Ailing Planet: the Green  Movement’s Role by Nani Palkhivala. This chapter is about environmental degradation caused by man's activities.

The rationale behind option (A) is the exact lines of the text, which read as follows:

We have shifted — one hopes, irrevocably — from the  mechanistic view to a holistic and ecological view of the world.

The word 'irrevocably' means permanently. Hence option (A) is the most appropriate in this context.