Some people are sitting on the grass; others are walking along the lake, ______

1. A.
   chatting and to laugh
2. B.
   to chat and to laugh
3. C.
   chatting and laughing
4. D.
   chatted and laughed

 Some people are sitting on the grass; others are walking along the lake, ______ .

     A. chatting and to laugh            B. to chat and to laugh 

     C. chatting and laughing               D. chatted and laughed