The school nurse is planning to begin an obesity screening program in a school system. It is best to begin the screening program with which group?

A. Kindergarten children may be too young for effective screening and intervention related to obesity. B. Third grade is an appropriate time as children are developing habits, and early intervention can prevent obesity-related health problems. C. High school students are often already established in their health behaviors, making earlier intervention preferable. D. Onset of puberty varies widely and may miss earlier opportunities for prevention.