Sorry but your 2nd question is totally wrong.. you said that unmyelinated will block first and according to you The C is unmyelinated so it should be blocked first, but you said that B will block first.. now let me clear your confusion, the mylienated fibers will be blocked first as LA is work on node of Ranvier and non mylienated shows most resistant to LA. So the sequence is, A(gama=Delta> alpha=beta)> B> C.
Sorry but your 2nd question is totally wrong.. you said that unmyelinated will block first and according to you The C is unmyelinated so it should be blocked first, but you said that B will block first.. now let me clear your confusion, the mylienated fibers will be blocked first as LA is work on node of Ranvier and non mylienated shows most resistant to LA. So the sequence is, A(gama=Delta> alpha=beta)> B> C.