Answer:
The correct answer is - d. the idea that substances can produce germs on their own.
Step-by-step explanation:
Spontaneous generation is an obsolete theory or idea that supports the production of living things and substances from non-living substances and things.
This purpose is that the living creatures could arise from nonliving matter. In microbiology, it is an idea that says that substances can produce germs on their own even if the substances are not similar.