—Dad, I've got an "A" in the geography exam.

—That's a good _________. Keep it up. [ ]

A. suggestion

B. advice

C. reason

D. beginning.

据调查，旅游黄金周到青岛来旅游的游客大多来自山东省的各地市及周边省市，这说明旅游资源具有有限的        

A．环境承载量

B．地区接待能力

C．最优吸引半径

D．经济容量