Charles Had Never Been Especially Close to His Nightshift Coworkers

Charles had never been especially close to his nightshift coworkers until a massive ice storm followed by a blizzard shut down the city for days, blacking out power and making travel, even by foot, extremely hazardous. Suddenly, they pulled together, sharing resources and otherwise acting as a mutually supportive group while they remained stranded. This shows that

A) primary groups are very fluid and can change in response to circumstances.
B) in today's complex society, the distinction between primary and secondary groups is no longer useful.
C) secondary groups can take on the characteristics or primary groups in times of high stress.
D) Charles had underestimated the group's cohesiveness and had simply been an isolate.