Given below are four jumbled sentences. Pick the option that gives their correct order. 
A. So he told his son that for every careless act of his he would hammer a nail into a wooden pillar in their house, and for every positive act he would pull out one nail.
B. The boy saw that the pillar was getting crowded with nails and realised his mistake.
C. A father wanted to inculcate a sense of responsibility in his careless son.
D. He resolved to change his behaviour and soon the nails started coming out, till there were none left.