Depression is the leading cause of suicide, __     __ in turn is the third leading cause of death among 15 to 24 year olds in the United States．

         A．who                        B．which                    C．that               D．what

Depression is the leading cause of suicide, ________ in turn is the third leading cause of death among 15 to 24 year olds in the United States．

1. A.
   who
2. B.
   which
3. C.
   that
4. D.
   what

Depression is the leading cause of suicide, __     __ in turn is the third leading cause of death among 15 to 24 year olds in the United States．

       A．who        B．which     C．that         D．what

Depression is the leading cause of suicide, __     __ in turn is the third leading cause of death among 15 to 24 year olds in the United States．

A．who           B．which          C．that         D．what

Depression is the leading cause of suicide, __    __ in turn is the third leading cause of death among 15 to 24 year olds in the United States．