They find themselves ________by colourful rocks, fishes, seashells and plants, all waving and moving slowly in the blue waters．

1. A.
   to surround
2. B.
   surrounding
3. C.
   surround
4. D.
   surrounded

They find themselves ________by colourful rocks, fishes, seashells and plants, all waving and moving slowly in the blue waters．

[　　]