Answer: Breaking down tasks into smaller, manageable parts
Step-by-step explanation:
The word decomposition means to break down so Problem decomposition means to break down the problem being faces into smaller parts with the reason being to be able to manage it better.
Some problems are simply too large to handle singularly because of the amount of resources that would have to be devoted. It would be better to break them down into smaller tasks that can then be be confronted one at a time with enough resources to solve them each.