Did Gjellerup write in his native language all his life?
No, he wrote in German in later life
Yes, he only wrote in Danish
He wrote in Swedish
He wrote in Latin
Answer
No, Gjellerup did not write in his native language all his life. He wrote in Danish early in his career, but later switched to writing in German. This was likely due to the fact that he was living in Germany at the time and wanted to reach a wider audience.
The Enigmatic Tales of Karl Adolph Gjellerup: A Journey through Danish Literature