What can help the police solve a case or find out who is the real criminal?

1. A.
   Fingerprints
2. B.
   Footprints．
3. C.
   Blood．
4. D.
   A．B and C

What can help the police solve a case or find out who is the real criminal?

A．Fingerprints     B．Footprints．    C．Blood．           D．A．B and C