An Example of Communal Sharing Is

An example of communal sharing is

A) people exchanging Christmas cards with their acquaintances.
B) buying something from Ebay,where the seller's relationship with the buyer is independent of price.
C) a family in which each person takes turns taking out the garbage.
D) an office with a water cooler,where each worker can take as much water as he or she likes.
E) the elder of a community giving away his wealth.