如图，一次函数y=kx+b的图象分别与反比例函数y= $\frac{a}{x}$ 的图象在第一象限交于点A（4，3），与y轴的负半轴交于点B，且OA=OB．

A: Hello Sandy This is Mary speaking, ____？

B. I'm Xi'an

A. Are you taking a holiday there?

B. Yes.  ____？

A: I'm writing a report.

B: ____?

A: It's about the population.

B: Well, I think you can write about the population of Xi' an.

A: Good idea. ____?

B: More than 8 million.

A: Is the population of Xi'an larger than that of Dalian?

B: ____Let me ask my father. Maybe he knows it.

A: All right.

亚太经合组织（即亚太经济合作组织，简称APEC）是亚太地区最具影响的经济合作官方论坛，现有成员21个，如图中阴影所示，APEC成员主要分布在（　　）