![](https://cos-cdn.shuashuati.com/pipixue-wap/2020-1230-1107-56/ti_inject-812ce.png)
The research in Paragraph 3 is mentioned to prove that
A.
to use a fan seemed to be effective for infants in high-risk environments.
B.
control infants are matched by county, race, ethnicity and age to the first group.
C.
fans improve ventilation and decrease the chance of rebreathing exhaled carbon dioxide.
D.
using a fan in high-risk environments, infants will no longer die of SIDS.