An analyst does research about efficient frontier curve. As an investor continues to assume more risk and moves upward on the efficient frontier, the slope of the efficient frontier curve:

A. increase and incremental return per unit of risk decrease.
B. decrease and incremental return per unit of risk increases.
C. decrease and incremental return per unit of risk decrease.

下列关于生物多样性的保护，正确的是（）

A.自然保护区的功能是接纳各地迁移和捕来的野生动物并加以保护

B.鼓励人们进入保护区，给鸟类建巢、喂食

C.迁地保护就是把大批野生动物迁入动物园、水族馆等进行保护

D.对于珍稀濒危物种，禁止一切形式的猎采和买卖