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Combinatorics Difficulty 3.0 AMC 10/12 Find the answer United Kingdom

From noon till midnight, Clever Cat sleeps under the oak tree and from midnight till noon he is awake telling stories. A poster on the tree above him says “Two hours ago, Clever Cat was doing the same thing as he will be doing in one hour's time”. For how many hours a day does the poster tell the truth?

(A) $3$ (B) $6$ (C) $12$ (D) $18$ (E) $21$

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