A、In 1938. B、In 1946. C、In 1955. D、During the World War II. B文中提到虽然举办这个电影节的想法在1938年就提出，但因为二战的影响，直到1946年才举办第一届电影节，故选B。

Cannes Film Festival, the most prestigious motion- picture festival in the world, is held each May in the city of Cannes, in southeast France.  The Cannes Film Festival was conceived at the end of 1938. Due to World War II, however, the first Cannes Film Festival was not held until 1946. Internationalism and postwar optimism characterized the first festival, as organizers placed less emphasis on competition than on mutual creative stimulation between national productions.  In later years the selection of entries for prizes reflected more commercial interests and the festival soon acquired its current reputation as a fashionable professional event, more concerned with advancing the film industry than the art of film. French director Francois Truffaut addressed this issue in 1956 and predicted its commercial death; The festival survived, however, and in 1959, Truffaut himself was awarded the prize for best screenplay for one of his films.
    Despite its ever present financial interests, the Cannes Film Festival remains an essential affair for international cinema. In 1955 the organizing committee at Cannes introduced the Golden Palm Award ( in English) for best film of the festival, now regarded as one of the film industry’s most distinguished prizes. Past recipients of the award include Taxi Driver by American director Martin Scorsese, The Piano by New Zealand director Jane Campion, etc.