Correct answer: D). Cells form through spontaneous generation.
Modern cell theory was given by Louis Pasteur and Rudolf Virchow, However, before the modern cell theory, it is believed that life starts to originate from spontaneous generation, which says that living organism originates from non-living matter.
According to the theory of spontaneous generation, it was known that dust has created fleas, and maggot arises from the rotten meat, wheat, and bread left in the dark corner produces mice.