Elephants have four distinct personalities that help their herd survive in the African bus

Elephants have four distinct personalities that help their herd survive in the African bush, scientists have found. 
With their grey skin, mournful eyes and slow heavy pace, you could be forgiven for thinking elephants are uniformly melancholy(忧郁的) creatures. But scientists have now discovered the largest living land animals have personalities to match their size.
In a new study of African elephants, researchers have identified four distinct characters that are mon in a herd – the leaders, the gentle giants, the playful rogues(小淘气) and the reliable plodders (辛勤工作的人).
Each of the types has developed to help the giant mammals survive in their harsh environment and is almost unique in the animal kingdom, according to the scientists.
Professor Phyllis Lee and her colleague Cynthia Moss studied a herd of elephants in the Amboseli National Park in Kenya known as the EB family — famous for their matriarch Echo before she died in 2009.
Using data collected over 38 years of watching this group, the researchers analyzed them for 26 types of behavior and found four personality features tended to emerge.
The strongest personality to emerge was that of the leader. Unlike other animals, where leadership tends to be won by the most dominant and aggressive individual, the elephants instead respected intelligence and problem solving in their leader. Echo, the matriarch and oldest in the group, her daughter Enid, and Ella, the second oldest female, all emerged as leaders.
The playful elephants tended to be younger but were more curious and active. Eudora, a 40-year-old female in the herd, seemed to be the most playful, consistently showing this feature throughout her life while playfulness in some of the other elephants declined with age.
Gentle elephants, which included two 27-year-old females Eleanor and Eliot, touched and rubbed against others more than the others.
Those that were reliable tended to be those that were most consistent at making good decisions, helped to care for infants in the herd and were calm when faced with threats. Echo and her youngest daughter Ebony seemed to be the most reliable.
Professor Lee said that elephants with these features tended to be the most socially integrated in the group while those who tended to be less reliable and pushy were more likely to split from the herd.
【小题1】From the passage we get to know that     .A．the researchers reached their conclusion by analyzing the dataB．the research centered on the 26 types of behavior of the matriarchC．the scientists conducted the research by paring elephants with other animalsD．professor Phyllis Lee and her colleague spent nearly 38 years tracking the herd【小题2】According to the new findings of the scientists,     .A．playfulness of an elephant will always decline with ageB．those elephants which are caring and wise are most reliableC．each elephant can be matched with only one of the four personalitiesD．once being a member of a herd, an elephant will never split from it【小题3】In the EB family Echo and Eudora are     .A．mother and daughterB．two oldest femalesC．the gentlest onesD．leader and memberA