Assertion: Consciousness is considered as the defining property of living organisms. Reason : All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental stimuli.

Step-by-step solution

Consciousness is awareness of the surroundings and responding to external stimuli. The external stimuli can be physical, chemical or biological. All organisms, from primitive prokaryotes to most advanced and complex eukaryotes, are able to sense and respond to environmental factors. Consciousness is thus said to be the defining property of living organisms.