【单选题】

Questions 7 to 10 are based on the following conversation.At the end of the conversation, you will be given 20 seconds to answer the questions. Now, listen to the conversation.

What are the people discussingA．Whether or not snowflakes can be analyzeD、
B．How snowflakes are formeD、
C．What causes a snowstorm.
D．Where the largest snowflakes can be foun