A、The reproductive cycle of barnacles. B、A new source of protein. C、Types of sea animals. D、The adhesive quality of barnacles.

M: Did you watch" Undersea Discovery" last night?
W: No, I missed it. Did you?
M: Yeah. It was pretty good--it was about barnacles.
W:  Hmm.
M: You know how they stick themselves to stuff in the ocean－like rocks or boats?
W:  Uh-huh.
M: Well, they do that when they’re young, and then they stay in the same place forever.
W: It figures. Have you ever tried removing one of those things? Last summer I tried to scrape some off a pier—I had to give up after a while. You’d think they wouldn’t be able to stick like that underwater.
M: Yeah. These biomedical researchers were talking about its possible uses. Orthopedists could use it for mending broken bones; or it could be used in dentistry.
W: I wish I’d seen that.