As a Cultural Phenomenon,the Notion of Adoption or Exchange of Children

As a cultural phenomenon,the notion of adoption or exchange of children is fairly common in Canada today.What is its status in other cultures?

A) It has only been practised by roughly 20 percent of the world's cultures.
B) While it is quite rare in some cultures,it is very common in others.
C) It is a universally common phenomenon practised by all cultures.
D) In most countries,it is simply an informal arrangement with no legal status.