In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: How old was Charlotte's husband when Prince Nikolaus died? Passage:In 1905, Grand Duke Adolphe's younger half-brother, Prince Nikolaus Wilhelm of Nassau, died, having left a son Georg Nikolaus, Count von Merenberg who was, however, the product of a morganatic marriage, and therefore not legally a member of the House of Nassau. In 1907, Adolphe's only son, William IV, Grand Duke of Luxembourg, obtained passage of a law confirming the right of his eldest daughter, Marie-Adélaïde, to succeed to the throne in virtue of the absence of any remaining dynastic males of the House of Nassau, as originally stipulated in the Nassau Family Pact. She became the grand duchy's first reigning female monarch upon her father's death in 1912, and upon her own abdication in 1919, was succeeded by her younger sister Charlotte, who married Felix of Bourbon-Parma, a prince of the former Duchy of Parma. Charlotte's descendants have since reigned as the continued dynasty of Nassau, and also constitute a cadet branch of the House of Bourbon-Parma.
 Links: a. Dynasty b. William IV, Grand Duke of Luxembourg c. Marie-Adélaïde, Grand Duchess of Luxembourg d. Prince Felix of Bourbon-Parma
A: 
d