Answer:to identify there self like for people to know they are an indigen of a state, and for slavery in the past the owner uses tribal mark to identify it property, and for children in the past the Yoruba's believed in abiku so when the child die they give him the mark in case it came back
B) because when traders sell slaves they would make the highest profit they could whether it be 50 cents to 50 dollars. In this situation he got them for free it appears so he would make a profit in any way.