Ok ty for pts anyway the answer is at commnet
When you enumerate you need to put comas between all the items except the ones which are connected by "and" : as A is not correct as it does not have comas, and B is incorrect as it has comas where "and" is.
now, in a way both C and D are correct, but C is the usual accepted version, and D is an example of "Oxford coma" (where the coma is optional, to remain on the safe side, choose C).
Because the rain stopped, we ran outside to play Capture the Flag.
english is the answer... thats why
