We are taught to be in C for any pick off at 3rd, because it is the more important play. Plus on a hit it is easy to pick up the R1 and take him into 3rd.
CCA manual teaches B, I disagree with C position. However, that's what you're taught that's what you do. CCA also teaches that in R1/R3 situations, PU will have any play at 3rd on R1. I personally would've held true to my call and not went for help in that situation, and he's now on a very short leash with me.