Which NIST cloud service model is this?

A user is provided access over the internet to an application running on a cloud infrastructure. The servers, databases, and code of that application are hosted and maintained by the vendor.

Which NIST cloud service model is this?
A . IaaS
B. SaaS
C. PaaS
D. CaaS

Answer: B

Explanation:

SaaS – User responsible for only the data, vendor responsible for rest