Final answer:
When burns are described as combined degrees, the coder should choose the most severe code.
Step-by-step explanation:
When burns are only described as combined degrees, the coder should choose the most severe code.
This is because the most severe code represents the highest degree of burn.
For example, if a burn is described as a combination of a second-degree burn and a third-degree burn, the coder should select the code for a third-degree burn as it is more severe than a second-degree burn.