Definition: In this task you are given a small conversation between two persons and 4 options on how the conversation should continue. Your job is to choose the most reasonable option. The conversation and the options are separated by a newline character. Each dialogue in the conversation are separated by a comma. F and M indicate female and male, respectively.
Input: 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. ,F: I've always wondered if there is an end in space. Do you think scientists have found the answer? ,M: This is a difficult question. The truth is that we have no idea. We currently don't have a way of testing it. But some scientists will come up with a way in the future. I have faith in it. ,F: The last question is from our readers. Do you believe there is other life in different parts of the universe? ,M: There are so many planets in the universe. Life may exist on other planets, but will we ever find or research them? I think that's very unlikely.
(A) F: Why do you think it is easy to find life elsewhere, since you are my best teacher in school. (B) F: Since you are a scientist, why do you think it is impossible to find life elsewhere? (C) F: I also think it is exciting to find life elsewhere, let us go to school and tell our teachers. (D) F: I didn’t hear you. Please could you tell me again?

D