Who should have this?
 

Opening tip, 3 man, I'm R.
Tip goes to A1 in her FC, who then immediately passes it to A2 in the BC. I'm R, and by the time I get my bearings, I'm watching A2 catch the ball and thinking, "I think she was in the FC, crap!" Just then C, who is coming from the BC to slide into the slot, hits his whistle and gets the call.

I don't see anything wrong with the way it was handled
 

Since you have to wait to clear the "wash" I see no reason C shouldn't get this. I don't have my mechanics manual with me. This may be by the book your call, but I can argue for the C making this call. It certainly can't be the lead even if it was on his side as he is moving to the endline. This looks better coming from the C. Besides, you probably didn't have your whistle in your mouth yet.

I would say: anyone with a whistle in his or her mouth, given how fast it happened.