Child Deaths in the U.S.

According to the CDC,

the leading cause of death for children 1-14 years of age in the United States (2010) was "unintentional injury."

"Unintentional MV Traffic" is the leading cause of "unintentional injury" deaths for all children 1-14.
Specifically for children 1-4 years old, the leading cause of unintentional injury deaths is:

a) "Unintentional Drowning"
b) "MV Traffic"
c) "Homicide Unspecified"
d) "Unintentional Fire/Burn"

Sources:
http://www.cdc.gov/injury/wisqars/pdf/10LCID_All_Deaths_By_Age_Group_2010-a.pdf
http://www.cdc.gov/injury/wisqars/pdf/10LCID_Unintentional_Deaths_2010-a.pdf
http://www.cdc.gov/injury/wisqars/leadingcauses.html 

Answer: (a) "Unintentional Drowning"