When is an A a C and vice versa?

I haven’t been able to complete this model because I can’t determine the R.

I’ve been trying to figure out where I went wrong and it recently occurred to me that maybe the C was actually the A and then I began to wonder how to tell when an A is the C and vice versa.

So here’s the model as I had it:

C: Ate one cupcake
T: I shouldn’t have eaten that.
F: Guilt
A: Watched TV
R: ??