Answer: Option B
:
B
Living cells and organisms exhibit metabolism. However, metabolic reactions can be demonstrated outside the body in cell-free systems. An isolated metabolic reaction outside the body of an organism, performed in a test tube is neither living nor non-living. Hence, while metabolism is a defining feature of all living organisms without exception, isolated metabolic reactions in vitro are not living things, but are rather just living reactions. Growth or an increase in mass can be observed in living things. However, non-living objects also grow if we take anincrease in body mass as a criterion for growth. Mountains, boulders and sand mounds grow, although this kind of growth exhibited by non-living objects is through anaccumulation of material on the surface. In living organisms, growth is from inside. Growth, therefore, cannot be taken as a defining property of living organisms.Perception of events happening in the environment or the being conscious of the environment, however, is an exclusive characteristic of living things. All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental cues.