An organized set of investigation procedures is called a
scientific investigation
scientific theory
scientific procedure
scientific method

An organized set of investigation procedures is called a scientific method.

There are five steps of the scientific method for an experiment.

Step 1: Make a question

Step 2: Do some research for that question.

Step 3: Hypothesis ( a guess what might happen during the experiment)

Step 4: Test and collect data

Step 5: Conclusion ( what you learned from the experiment)

if you already have the answer to (a), then just work out how many periods there are in 1 minute, and that's the answer to (c).