Final answer:
Ilona Elek retained her Olympic fencing title in 1948 after the previous Games were held in 1936. The 1940 and 1944 Olympic Games were cancelled due to World War II.
Step-by-step explanation:
In 1948, Ilona Elek retained her Olympic fencing title, an impressive feat considering that the previous Olympic Games were held in 1936.
During the 1940s, World War II disrupted the staging of the Olympics, resulting in the cancellation of the 1940 and 1944 Games.
Therefore, the correct answer is d) 1940.