Because Astronomers use light-year instead of kilometers to measure distances in the universe because distances in space are so huge that km would be too large to manage.
The answer I believe would be A
In both species repeated pairing of a CS and US eventually produces a CR in response to the CS alone. In the sea-slug this is a very direct process, in the species we have been discussing in these lectures - rats, dogs, humans and so on - I hope you have seen that it is far from being so simple.
Answer:
Christopher Columbus thought there was a westward route to Asia.
Hope this helped :)
