The correct answer is A. per gigabyte.
A cost model for a DBaaS is a way of determining how much the user pays for the database service. Different cost models may have different pricing factors, such as storage usage, data transfer, compute resources, and additional services.
A per gigabyte cost model is best for a cloud solution because it allows the user to pay only for the amount of storage space they use for their database. This way, the user can scale up or down their storage needs as per their requirements and budget. A per gigabyte cost model also reflects the actual cost of the infrastructure, software licenses, and maintenance that the service provider incurs to host and operate the database1.
A per seat cost model is not suitable for a cloud solution because it charges the user based on the number of seats or licenses they purchase for the database service. This means that the user may end up paying for more seats than they actually use, or not have enough seats to accommodate their users. A per seat cost model also does not account for the storage usage or performance of the database.
A per user cost model is also not suitable for a cloud solution because it charges the user based on the number of users who access the database service. This means that the user may have to pay more if they have a large number of users, or less if they have a small number of users. A per user cost model also does not account for the storage usage or performance of the database.
A per device cost model is also not suitable for a cloud solution because it charges the user based on the number of devices that connect to the database service. This means that the user may have to pay more if they have multiple devices per user, or less if they have one device per user. A per device cost model also does not account for the storage usage or performance of the database.