The correct answer is option 'C' - Francesco Redi. Let's explain why.

Introduction:
Spontaneous generation was a widely accepted theory in the 17th century that proposed living organisms could arise spontaneously from non-living matter. This theory was commonly believed for the generation of bacteria from decomposing broth. However, in the 19th century, several scientists conducted experiments to disprove this theory.

1. Francesco Redi's Experiment:
Francesco Redi, an Italian physician, conducted an experiment in the late 17th century to challenge the idea of spontaneous generation. He hypothesized that flies were responsible for the appearance of maggots on decaying meat, rather than the meat generating the maggots spontaneously.

- Experiment Setup:
Redi performed two experiments. In the first experiment, he placed meat in two jars - one covered with a fine mesh and the other left open. He observed that maggots only appeared on the meat in the open jar, while the covered jar remained free of maggots. This supported his hypothesis that flies were necessary for the generation of maggots.

2. Louis Pasteur's Experiment:
Although Redi's experiment provided evidence against spontaneous generation, the theory was still debated. It wasn't until Louis Pasteur's experiments in the mid-19th century that the theory was definitively disproven.

- Experiment Setup:
Pasteur used a curved-neck flask, known as a swan-neck flask, in his experiment. He boiled a nutrient-rich broth in the flask, sterilizing it and killing any existing microorganisms. The long, curved neck of the flask allowed air to enter but prevented dust particles and microorganisms from reaching the broth. Pasteur observed that no bacterial growth occurred in the broth, demonstrating that the broth remained sterile as long as it was not exposed to contaminated air.

Importance and Conclusion:
Redi's and Pasteur's experiments were crucial in disproving the theory of spontaneous generation:

- Redi's experiment challenged the idea of spontaneous generation by showing that living organisms do not arise spontaneously from non-living matter.
- Pasteur's experiment provided further evidence against spontaneous generation and demonstrated the importance of preventing contamination from airborne microorganisms.

Overall, the experiments conducted by Francesco Redi and Louis Pasteur played a significant role in discrediting the theory of spontaneous generation, leading to a better understanding of the process of life and the principles of microbiology.