W.H.O. assists different national health authorities not only in controlling diseases but also in preventing them, altogether. The above sentence implies that

• A. W.H.O. assists more in preventing diseases than in controlling them.
• B. _assists in controlling diseases only if they have not been prevented_
• C. W.H.O. assists both in controlling diseases and in preventing them.
• D. W.H.O. assists many others in addition to the national health authorities