arguments in philosophy. chemical analysis of material. examining models of the process. conducting a controlled experiment.
I gave my students this multiple choice question: The theory of spontaneous generation was eventually disproved scientifically by

Only one answer is correct among these 4 choices:
- arguments in philosophy.
- chemical analysis of material.
- examining models of the process.
- conducting a controlled experiment.

Could you tell me which one is correct?

conducting a controlled experiment.