Answer:
The work of Alexander Fleming shows that not all scientific knowledge begins with an experiment (option b).
Step-by-step explanation:
In the 1920s, Alexander Fleming, almost by accident, discovered a naturally growing substance that could attack certain bacteria. In one of his experiments, Fleming observed that colonies of a bacterium had been depleted or removed by a mold that grew on the same Petri dish. He noted that bacteria furthest from the fungus had grown to produce large-sized colonies, while colonies closest to the fungus were tiny. In this way Fleming determined that mold made a substance that could dissolve bacteria. So Fleming called this substance penicillin, by the name of the fungus (penicilium chrysogenum) that produces it.
So, as you can see, the discovery of penicillin was accidental, without a specific experiment planned for its discovery.
Then, the work of Alexander Fleming shows that not all scientific knowledge begins with an experiment (option b).