The correct answer is C) decide how you can use the source.
The last step to breaking down a source is "decide how you can use the source."
After carefully reading the information contained in the source, you will understand its content and then you can find the main topic. Then, knowing what your information necessities are you can decide if the content of the source is valid, appropriate, and fits your necessities. If this is so, then the source is useful and it becomes part of your research. That is why it is important to have a pull of sources that allows you to decide on the best alternative.
The other options of the question were A) read the source carefully. B) Analyze the source in detail. D) Determine the main idea of the source.