______ from the top of the tower, the south foot of the mountain is a sea of trees

1. A.
   Seen
2. B.
   Seeing
3. C.
   Having seen
4. D.
   To see

._____ from the top of the tower ,the south foot of the mountain is a sea of trees .   

   A.Seen    B.Seeing  C.Have seen    D. To see

______ from the top of the tower, the south foot of the mountain is a sea of trees.

_____ from the top of the tower, the south foot of the mountain is a sea of trees.

_____ from the top of the tower, the south foot of the mountain is a sea of trees.