Benjamin Bloom in His Study of American's Top Concert Pianists

Benjamin Bloom in his study of American's top concert pianists, tennis players, and Olympic swimmers found that​

A) ​when they were children their skills were rather ordinary at first.
B) ​their talent just "magically" surfaced one day.
C) ​the majority of them were not exposed to expert coaching until they were older adolescents or young adults in national competitions.
D) ​they require less practice of their craft each day than a successful, but less eminent, person in their field.