to contrast the concern the boys should have felt with the satisfaction they really felt.. It can be seen the boys ere very happy when the cubs boat blew up and when the cub appeared in church and was treated as a hero.
If you accept either C or D as the correct revision then you have to accept both of them. Hence the best way to treat the sentence is to ignore both of them.
B is not correct either. You can over punctuate.
That leaves A.
Sometimes the right answer to many things is to do nothing. My dad used to say "Don't fix what isn't broke."
A is the answer <<<<<
