TASK DEFINITION: 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.
PROBLEM: Context: such as the Swiss band Hellhammer (later to become Celtic Frost) Link Information:  Formed in 1981 as Hellhammer, the band became Celtic Frost in 1984 Answer: 1984

SOLUTION: In what year did Hellhammer become Celtic Frost?

PROBLEM: Context: n Indiana, where it is illegal to create a historical marker in the "state format" without first getting official approval from that state's historical bureau Link Information: none Answer: none

SOLUTION: How many historical markers does the state of Indiana have?

PROBLEM: Context: Blachstein was also affected more directly by the intense political tensions radiating out from Moscow, based on Stalin's suspicions - not entirely unfounded - that there might be comrades in the Soviet Union and further west in Europe who favoured an alternative Soviet leader. Link Information: Lenin died in January 1924. Stalin took charge Answer: 13

SOLUTION:
How long had Stalin been the leader of the Soviet Union by the year 1937?