Final answer:
Platform as a Service (PaaS) is the best option for a firm to develop, test, and deploy software in the cloud, offering a comprehensive environment with all necessary tools integrated into the platform.
Step-by-step explanation:
To assess the best cloud-based option for your firm to develop, test, and deploy software, it's essential to understand the strengths of the available service models. The most appropriate service for these requirements is Platform as a Service (PaaS). PaaS provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.
It's an all-encompassing environment that includes networks, servers, storage, and other services-and is particularly effective for software development cycles, with various tools for development, testing, and deployment integrated into the platform.
Comparatively, Software as a Service (SaaS) would not be adequate for development purposes as it mainly offers ready-to-use software applications over the internet. Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet and, while customizable, would require additional setup for development environments. Thus, for the specific needs of developing, testing, and deploying software, PaaS stands out as the optimal choice.