There are five women in the school who are applying for the position of a dance teacher. Two of them are over 30 years old, and the other three are younger than 30 years old. Two women have been Teachers, the other three have been secretaries in the past. Now I only know that: A and C belong to the same age group, and Ding and Wu belong to different age groups. B and E have had the same occupations, and C and D have different occupations. The principal wants to choose a lady who is over 30 years old and has been a teacher as a dance teacher. Who will be the lucky one? ['B.', 'C.', 'Ding.', 'E.']