Your teacher gives you a task in science class. You must decide which of the five samples you are given are alive or were once alive. One specimen is a crust gray-green object. What is the BEST clue you could use to decide: living thing or not a living thing. A) Does it move?
B) Does it have DNA?
C) Is it made of cells?
D) Can it make its own food?

The best clue that can be used to decide living thing or not a living thing is the observation of living or dead cells present in the specimen. All the living or dead organisms exhibit cells. Cell is a structural and functional unit of life. The growth and metabolism of living organism are dependent upon a cell. A cell in a life form exhibit organelles and components which are not found in non-living objects