Answer: hypothesis, prediction, design experiment, carry out experiment, etc
Explanation:If the question is supposed to be, is there a connection between atmospheric oxygen level and photosynthesis, then the next step would be to frame the hypothesis, which could be, for example,
“photosynthesis requires oxygen”, and a prediction such as,,
in a closed system, photosynthesis will reduce the oxygen level, or even photosynthesis does not proceed without oxygen.
and a format to test the hypothesis (design an experiment)
perform the experiment
collect data
analyse data
(of course, in this case, the data will support the null hypothesis).