Answer:
The correct answer is - He only tested one subject, so his conclusion is not valid.
Explanation:
In the given question there is an experiment where Joey developed medicine for curing cancer. He tested the medicine on a cancer patient but his results did not publish in the journal as the experiment is not reliable as he tested on a single subject.
The tests or experiments should have performed on different subjects to test the reliability of the results. Single-subject experiments are not trustworthy as there can be other factors or physical condition can help the subject other than medicines.
