Your definition is for option A: a collection of (azure) policy definitions.
Jishnu9694▲ 9Highly votedAugust 22, 2021 10:25 am
WRONG - B IS CORRECT ..An Azure Policy initiative is a collection of Azure Policy definitions, or rules, that are grouped together towards a specific goal or purpose. Azure initiatives simplify management of your policies by grouping a set of policies together, logically, as a single item.
https://docs.microsoft.com/en-us/azure/governance/policy/overview#initiative-definition