Given the task definition and input, reply with output. Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.

Context : The GCR Class 1 was a class of steam locomotives designed by John G. Robinson for the Great Central Railway, and introduced to service between December 1912 and 1913.
Answer : December 1912
What was the year that GCR Class 1 entered service?