Final answer:
The researchers were testing the hypothesis that harvesting fish randomly would decrease the size of fish in future generations.
Step-by-step explanation:
The hypothesis that the researchers were testing in the section 'Investigating Life: Size Matters in Fishing Frenzy' is option B. Harvesting fish randomly would decrease the size of fish in future generations.
The researchers wanted to investigate the impact of random fishing on the size of fish in future generations. They hypothesized that if fish were harvested randomly, it would lead to a decrease in the size of fish in future generations.
To test this hypothesis, the researchers likely conducted experiments or observed fishing practices where fish were randomly harvested and measured the size of the resulting fish populations over time. By comparing the data from these experiments, they would be able to determine if random fishing had an impact on the size of fish in future generations.