In Essence,most of the Extrasolar Planets Discovered to Date Have

Multiple Choice

In essence,most of the extrasolar planets discovered to date have been found by

A) closely examining very high-resolution photographs of other star systems.
B) observing a star carefully enough to notice that it is experiencing a gravitational tug caused by an unseen planet.
C) identifying spectral lines that look like what we expect to see from a planet rather than a star.
D) observing mini-eclipses of a star as an unseen planet passes in front of it.