Measurements Suggest That Light First Arrived at Earth from the Cassiopeia

Multiple Choice

Measurements suggest that light first arrived at Earth from the Cassiopeia A supernova about 300 years ago and that this supernova is about 10,000 ly distant from Earth.When did the explosion actually occur?

A) It is not possible to determine when the explosion occurred from the information given.
B) 9700 years ago, or about 7700 b.c.
C) 10,300 years ago, or about 8300 b.c.
D) 300 years ago, or about a.d. 1700.