Explanation:

- Accommodation: This means adjusting or changing to suit the needs of children, but it doesn’t fully capture the mutual aspect of child-rearing.

- Co-operation: This is about working together, both parents and children, to create a positive environment. It emphasizes teamwork and understanding, which is essential when bringing up children.

- Integration: This usually refers to combining or blending things together (e.g., cultural integration). It's not specifically about child-rearing.

- Assimilation: This means absorbing or adapting fully to something, often losing individual traits, which is not the main idea in parenting.