Both B and D are correct forms - the last comma is optional.
I would use probably use a comma here because the brothers' tasks are so diverse. However, I am not forced to use it - it is optional.
I would not use it here:
I am considering a HP, Dell and Lenovo as possibilities for my next computer.
(Because they are not diverse - they are all brands of computers).
What's wrong with A - It sound as if your brothers dropped the dishes as they took them out of the dishwasher and had to clean up all those broken washed dishes.
C is wrong because of the unecessary common after the "and".
I dont understand sorry is that german or what
