If Observations of Supernovae in Other Galaxies Show That Such

If observations of supernovae in other galaxies show that such an explosion happens in a spiral galaxy like the Milky Way on average every 25 to 100 years, why have astronomers on Earth not seen a supernova explosion in our Galaxy since 1604?

A) we have been very unlucky; there have been far fewer explosions than average recently
B) all the explosions happened in that part of the sky which is only visible from the Earth's southern hemisphere, and we do not have any large telescopes down there
C) the disk of our Galaxy contains a great deal of dust, which tends to block the light of supernova explosions from more distant parts of our Galaxy
D) most supernova explosions produce only high-energy gamma-rays and very little light
E) actually, there have been supernova explosions observed, but there is a government conspiracy to keep ordinary citizens from learning about them (just like the alien creatures that were in Roswell, New Mexico and Area 51)