Brandon on October 28, 2018
Ans choice A (the apparent correct ans) says they are difficult to distinguish, but paragraph 2 seems to say that Physicists are confident they are picking up one and not the other. I'm not sure what i'm missing?
Mehran on October 31, 2018
jing jing on April 11 at 01:56AM
Ben on April 11 at 10:48PM