Final answer:
The most technical responsibility is held in IaaS (Infrastructure as a Service). It requires the user to have a deep understanding of the underlying infrastructure and its configuration.
Step-by-step explanation:
The most technical responsibility is held in IaaS or Infrastructure as a Service. In IaaS, the service provider offers virtualized computing resources such as virtual machines, servers, storage, and networking. The user has complete control over the infrastructure and is responsible for managing and maintaining it. This solution requires the user to have a deep understanding of the underlying infrastructure and its configuration, making it the most technically involved option.