Answer
The answer is incorrect. Belmondo's career was most prolific in the 1960s, not the 1930s. During this decade, he starred in numerous iconic films, including "Breathless" (1960), "That Man from Rio" (1964), and "Pierrot le Fou" (1965). These films established Belmondo as a leading figure in the French New Wave movement and cemented his status as one of the most popular actors in French cinema.