Answer:
Are produced only by living things.
Step-by-step explanation:
Theory of spontaneous generation explains that living organisms are produced from the inorganic matter. For example: rats are originated from the wheat.
The theory of sponatneous genereation is not valid and considered as a mistaken idea. The living organisms are produed from the other living organisms or produced from the organic mattter only.
Thus, the correct answer is option (B).