【单选题】

Questions 4 to 7 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.
According to Mr.Bacon. people keep snakes becauseA．they like them as pets.
B．they are curious of them
C．they use them to frighten other people.
D．they keep them to do research.