Answer:
The correct answer will be metabolism.
Step-by-step explanation:
The biologist tried to identify the characteristic features of living organisms which distinguished the living beings from non-living things.
The metabolism is one of the characteristic features of a living organism which produces energy for the living organism to survive. The metabolism involves the anabolism or the formation of complex molecules as well as catabolism or the breakdown of the complex molecules to simple molecules.
Since photosynthesis is a sequential chain of chemical reactions which helps in the production of energy molecules like glucose and ATP. Therefore, photosynthesis represents the process of "metabolism".