Answer:
The answer is a:
Send a robot to measure how much oxygen is dissolved in water at various depths, because the amount of oxygen dissolved in water changes with pressure.
Step-by-step explanation:
The hypothesis states:
"Less oxygen is dissolved in deeper layers of the ocean compared to shallower layers."
The hypothesis entails the investigation of the effect of depth and pressure on the dissolved oxygen (D.O) in the ocean. This hypothesis contains one dependent and two independent variables.:
Independent variables:
- Depth
- Pressure
Dependent variable:
- Oxygen
To plan an experiment, one must vary the depth and pressure to determine the changes in D.O.
- In option b, the depth and pressure of water in a beaker cannot be changed, so this experiment will not give proper results. It would basically measure the time dissolved oxygen stays in water.
- Option c would determine the amount of oxygen present in the tissues of fish living at different depths.
- Option d would determine the levels of oxygen different aquatic plants are capable of producing at varying depth and pressure.