Evidence has been piled up ________ specific speech sounds are recognized by babies as young as five months old．

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

Evidence has been piled up ____ specific speech sounds are recognized by babies as young as five month old.

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

 Evidence has been piled up ____ specific speech sounds are recognized by babies as young as five month old.

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

Evidence has been piled up ____ specific speech sounds are recognized by babies as young as five month old.

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