Which of the following had the earliest record on tuskless elephants?

A．Gorongosa National Park.

B．South Luangwa National Park.

C．Ruaha National Park.

D．Lupande Game Management Area.

解析：C　考查细节理解。根据第一段的第二句可知，在莫桑比克的Gorongosa国家公园，在1992年，有33%的雌象出生时无长牙；根据第三段尾句“A 2008 study published in the African Journal of Ecology found that the number of tuskless females at the Ruaha National Park in Tanzania went from 10.5 percent in 1969 to almost 40 percent in 1989, largely due to illegal hunting for ivory”可知，Ruaha国家公园在1969年有10.5%的无长牙雌象，到1989年时，有大约40%的无长牙雌象；据此可知，Ruaha国家公园是最早记录无长牙雌象的地区，故C项正确。

11．What does the underlined phrase “the trend” in the last paragraph refer to?

A．Elephants facing greater danger.

B．Elephants growing more slowly.

C．Fewer female elephants staying alive.

D．More female elephants being tuskless.

解析：D　考查推理判断。根据尾段第一句“The recent ban on ivory in both the US and China should help get rid of, or at least reduce, elephant hunting”可知，最近美国和中国都颁布了象牙禁令，这应该有助于消除或至少减少对大象的猎杀；结合该段第二句“However, scientists are not sure how long it will take for elephants with a higher rate of tuskless females, to change the trend”可知，科学家们并不确定对拥有较高比例无长牙雌象的大象们来说需要多长时间才能改变这种趋势。据此可推知，画线词指代“更多的雌象没有长牙”这一趋势，故D项正确。