Answer: Only a small fraction of stars that have planets.
Step-by-step explanation:
What is the transit method?
The transit method works by observing a preselected study of stars for any periodical reduction in observed brightness. If this reduction is observed in any of the selected stars it is possible that the star's observable brightness is being reduced by a planet passing in front of it.
Therefore, the answer is only a small fraction of stars that have planets.
Hope this helps!