Pierre's Adoptive Parents Had an Open Adoption Agreement with His

Pierre's adoptive parents had an open adoption agreement with his biological mother.However,he is six years old and has never met her.Why is this likely to be the case?

A) Open adoption agreements cannot be legally enforced.
B) Most birth mothers usually prefer to remain anonymous to their adopted children.
C) Most adopted children are reluctant to hurt their adoptive parents and thus do not seek contact with their biological ones.
D) Open adoption records are sealed until a child turns 18.