F: How do you know how old a star is? ,M: For most stars, we find its age from how big it is. We can know its size from the amount of light it puts out and its color. Then the size tells us how long a star will live. Big stars live a short life, while small stars live much longer.
(A) F: That is true. We can know the age of a tree from its size. (B) F: You are right. People can know the age of a star from its size. (C) F: I am really sorry, I did not catch that. Would you slow down, please? (D) F: Great. The light of the sun can tell us how old it is.
B