Which statement provides context or background information about the situation described in the text?

a) "M immediately locked its doors—with visitors inside, at first—and the search began."
b) "In those days, the Louvre was the largest building in the world, with more than 1,000 rooms."
c) "At one point, as many as 60 detectives worked the case."
d) "Though no one could piece together what had happened, everyone seemed sure of one thing: the theft could only be the work of a criminal mastermind."