Final answer:
The specific duration of the revivals of Gilbert and Sullivan's operas Pinafore and Gondoliers in Denmark after World War II is not documented in a way that aligns with the provided answer choices, and detailed historical records are required to give a precise answer.
Step-by-step explanation:
The revivals of Gilbert and Sullivan's comic operas Pinafore and Gondoliers in Denmark after World War II did not have a specifically documented duration that matches any of the provided multiple-choice answers (A. 6 months, B. 12 months, C. 18 months, D. 24 months). Instead, the performance history of these operas varies by production and location.
When discussing the longevity of specific theater productions, it is important to note that various factors influence the run time, such as public interest, critical reception, and financial viability. A revival's success and duration are also influenced by cultural significance and the particular social climate during which it is performed. While Gilbert and Sullivan's works enjoy enduring popularity, precise run times for specific periods and locales, like Denmark after WWII, require detailed historical records.
Therefore, the student's question cannot be provided without access to detailed historical records or documentation regarding the exact run times of these particular productions of Pinafore and Gondoliers in post-war Denmark.