Introduction:

The structural levels of organizations of the body include the cells, tissues, organs, organ systems, and the organism. Life on Earth has different levels of organization, such as a cell, population, community, ecosystem, and biosphere. Each of the levels of organization has its own emergent properties, which can be defined as characteristics that are present in the concerned level of organization.

Correct answer:

The lowest level of biological organization that biologists consider to be alive is a cell.

Justification for the correct answer:

Option (c) is “a cell.” This option is correct as the cell is the structural, functional, and the fundamental unit of life. A group of cells that have a common function arranges themselves to form a tissue. Two or more tissues form an organ that performs a specific function. A group of organs that functions together to perform a common task is called an organ system. Different organ systems make up a living organism. The emergent property of a cell is life. Hence, option (c) is the correct answer.

Justifications for the incorrect answers:

Option (a) is “a protein.” This is false because protein is not a level of biological organization as it does not have life. It is a biomolecule found in the cell. So, it is an incorrect option.

Option (b) is “DNA.” This is false as the DNA (deoxyribonucleic acid) is not a level of biological organization. It is another biomolecule found in the cell. So, it is an incorrect option.

Option (d) is “a multicellular organism.” This is false because multicellular organisms are composed of cells, which acts as the basic unit of life. Thus, it is not considered as the lowest level of organization. So, it is an incorrect option.

Option (e) is “a population of organisms.” This is false because a population can be defined as a group of similar organisms occupying a certain habitat. So, it is an incorrect option.

Hence, options (a), (b), (d), and (e) are incorrect.