Here's a problem to solve: Some instruments record oxygen levels in the ozone layer of Earth's atmosphere. Keeping a record of this data for many years is an example of

Among the 4 following options, which is the correct answer?

- A: building evidence through ongoing investigation.
 
- B: identifying a hypothesis that supports the data.
 
- C: making conclusions about evidence from results.
 
- D: proposing data that is easy to understand.
 