Belinda plans to study early childhood development. her decision was based upon her love of baby-sitting when she was in high school and looking after her young niece on the weekends. her brother brad disliked baby-sitting and tried to "get out of it" when it was his turn. most likely, belinda

i believe the answer is has developed skills and is thus more interested in child care than Brad.
When someone is genuinely interested in a certain task, that person is more likely to indulge themselves in things that would make them better at doing that task. In this case, it would be things such as skills to handle the children or learning psychological tricks to help them understand the children.