Planetary Transits of Exoplanets Are Rare Because

Multiple Choice

Planetary transits of exoplanets are rare because

A) most extrasolar systems are not seen edge- on.
B) our telescopes are not powerful enough to detect them.
C) most stars are too bright for us to detect a planetary transit.
D) the Earth's atmosphere interferes with our observations of transits.
E) most exoplanets are smaller than Pluto.