Answer:
b) organized contests
Step-by-step explanation:
Subcategory refers to a subdivision included in a larger category. It is also a secondary category.
When we list all of the enumerated objects, we can see that all are the same kind of contest where the participants can fight or compete for the trophy or win the first, second or third place. These objects are words that refer to some kind of competition and they must be organized so that participants can be prepared and registered.