Answer:
The AWNSER IS a TO INFROM
Explanation: the reader was trying to inform that slaves were so popular in other parts of the world
Dear Mr /Mrs principal
I was walking last day and I seen same boys was painted the wall and I am the witness of it.
thanks
xyz.
Complex sentence because 'when i visited Issac's house' could not be a sentence on its own but 'his parents gave me a warm welcome' could