Final answer:
Jeff can scientifically investigate which organisms are part of the food web in the pond, construct a food web diagram, and predict changes to the ecosystem if an organism is removed.
Step-by-step explanation:
Among the questions Jeff has about the pond, the one he can answer through scientific investigation is A. Which organisms are part of the food web in the pond? By observing the pond, collecting samples, and researching, Jeff can identify the different organisms and their relationships within the pond's ecosystem. This will allow him to construct a diagram of the food web, showing how matter and energy flow between producers, consumers, and decomposers. Removing an organism from the diagram can help Jeff predict changes to the ecosystem, such as if a primary consumer is removed, the producers may overpopulate, or if a top predator is removed, there may be an increase in the population sizes of organisms lower in the web. These investigations of the aquatic ecosystem would incorporate understanding trophic levels and the role of each organism in the web.