The correct answer is 'Cool tier in a general-purpose v2 storage account' because cool storage is optimized for storing data that is infrequently accessed and stored for at least 30 days. It provides a cost-effective solution for storing large volumes of data that do not require the low latency of hot storage. A general-purpose v2 storage account supports all the latest storage options and performance tiers. The incorrect answers include options that do not optimize cost for infrequently accessed data or that support only specific data types.