![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
What do we learn about the international scientists'research?
A.
They kept detailed records of all the elephants.
B.
They compared zoo-born elephants with wild ones.
C.
They explain clearly why wild elephants are healthier.
D.
They focus on female elephants captured in the wild.