instruction:
In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.
question:
Context: the group originally included lead vocalist Keith Relf Link Information: The Yardbirds are an English blues rock band from London. Formed in May 1963, the group originally included lead vocalist Keith Relf Answer: Robert Plant
answer:
Which person was the lead singer of the Yardbirds the longest?


question:
Context: the Harvard Business School (M.B.A. Link Information: The school was established in 1908.  Answer: 1908
answer:
When did the school Cerny got his M.B.A. open?



question:
Context: The duke's son William, who succeeded his father in 1785 Link Information: Catherine II (; – ), also known as Catherine the Great (), born Princess Sophie of Anhalt-Zerbst, was Empress of Russia from 1762 until 1796 Answer: 11
answer:

How long did Catherine the Great rule for after William succeeded his father?