Astronomy question.?

Question

When we observe a distant galaxy whose photons have traveled for 10 billion years before reaching Earth, we are seeing that galaxy as it was when the universe was

A) 7 billion years old.

B) 4 billion years old.

Answer 1

Neither, you stated in your question that the "photons have traveled for 10 billion years before reaching Earth."    The Earth is just a very small part of another galaxy called the Milkey Way.  Sure enough, it is thought that the Earth, and the other planets are very young, only about 4.5 billion years old.  With the sun being a little older.    

Therefore, the galaxy you're speaking of, we are seeing as it was when the "galaxy" (not the universe) was 10 billion years old.  The Universe, I believe, is inconceivably old, much, much older than just a mere 10 billion years.  Maybe ever 13 million, or so, or it is thought, by people who are much, much smarter that I am.

Answer 2

Our latest figure on the age of the universe is 13.7 billion years. So 4 billion would be the closest.

http://map.gsfc.nasa.gov/news/