Which conclusion can be drawn from early education and intervention programs?

(a) Intervention programs that placed emphasis on motor, language, and social skills as well as cognitive skills, including literacy and math were correlated with higher reading and math scores in elementary school.

(b) Intervention programs that placed emphasis on preconventional reasoning skills were correlated with higher rates of confident and independent students in elementary school.

(c) Intervention programs that placed emphasis on the mutual exclusivity in learning were correlated with higher reading and math scores in elementary school.

(d) Intervention programs that placed emphasis on rigid academics were correlated with higher rates of confident and independent students in elementary school.