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.

Input: Consider Input: Context : An order to enter the BTR-60P into Soviet Army service was issued on 13 December 1959.
Answer : 13 December 1959

Output: What year did BTR-60 come into use?

Input: Consider Input: Context : In 1994, the U.S. military officially accepted the XM4 into service as the M4 carbine to replace M16A2s in certain roles.
Answer : 1994

Output: In which year was the service entry date for M4 carbine?

Input: Consider Input: Context : ''The Serenity Now'' is the 159th episode of the NBC sitcom Seinfeld.
Answer : Seinfeld
Output: What series is The Serenity Now part of?