Why is coronagraphy a powerful technique for searching for life on exoplanets?

a. It is sensitive to small motions of the parent star and therefore can detect terrestrial planets.
b. It is able to measure the size of a planet.
c. It blocks out the glare from the parent star so that terrestrial planets can be detected.
d. It will allow us to take spectra of the deep atmosphere of terrestrial exoplanets.