补全对话；从方框内所给句子中选择恰当的句子完成下面对话，并将其代表字母涂（填）在答题卡（纸）的相应位置。

( At the doctor's)

A: Good morning.

B: Morning doctor.

A:____ 

B: I'm not feeling very well.

A: Oh, let me see… ____  You are just overweight.

B: Really? But I don't eat too much.

A:____  You often eat sweet food and meat, don't you?

B: Yes, both of them.

A: To keep fit, you'd better eat less sugar but more vegetables. ____ 

B: OK, I'll do like that.

A: ____ .

B: Thank you very much.

生物多样性对人类的生存和发展的价值是巨大的，保护生物多样性最为有效的措施是

出现上述现象的原因最可能是（　　）

____