You have a problem deciding if the answer is B or D because they are saying much the same thing.
C is never going to be the answer: he will always remember the jungle just as you or I would remember our childhood. What we experience in childhood is the only experiences we are going to get from childhood. Reading about others will not do us much good.
A is not the answer although it is correct. Kaa and Shere Khan remain dangerous now as they were before. So A is not the answer you seek.
D is probably the answer you want. It is more general than B.
