Response:
Louis Pasteur, by noting that microbes existed in the air and were contaminating the broth contributed to the understanding that all cells arise from pre-existing cells (option b), which is a key postulate of the cell theory.
Clarification:
Pasteur's work, executed around 1860, demonstrated that unicellular life forms could be found in a sterile broth solely after it was exposed to air, where other microbes were present, thereby disproving the premise of spontaneous generation.
Conversely, in the broth that did not come into contact with the air, Pasteur did not find any microorganisms.
Through his experimentation, Pasteur rejected the idea of spontaneous generation and supported the postulate of the cell theory that suggests all cells derive from existing cells.
The other options are incorrect because:
a and c. Every living thing is composed of cells and the cell is the fundamental functional unit of living organisms are tenets of cellular theory not validated by Pasteur's research.
d. Unicellular organisms inherit exact copies of DNA from their parent cell does not represent a postulate of cell theory.
