The answer is the first one (A): Virus.
Explanation for each option:
A. Virus: Viruses are not considered living things because they cannot carry out metabolic processes on their own. They require a host cell to replicate and do not exhibit characteristics of life such as growth, energy production, or response to stimuli independently.
B. Bacteria: Bacteria are considered living organisms. They are single-celled microorganisms that can carry out all necessary life processes, including metabolism, growth, and reproduction.
C. Plant: Plants are living organisms. They are multicellular and can perform photosynthesis, grow, reproduce, and respond to their environment.
D. Animal: Animals are living organisms. They are multicellular, can move, grow, reproduce, and respond to their environment.
Summary:
Viruses are not considered living things because they cannot perform life processes independently and require a host cell for replication. Bacteria, plants, and animals are all considered living organisms.