He not only has a first-class brain but is also a tremendously hard worker.
A.Not only he has a first-class brain but is also a tremendously hard worker.
B.Not only does he have a first-class brain but also a tremendously hard worker.
C.Not only does he have a first-class brain but he is also a tremendously hard worker.
D.Not only does he have a first-class brain but is also a tremendously hard worker.