A company wants to protect a specialized legacy platform that controls the physical flow of gas inside of pipes. Which of the following environments does the company need to secure to best achieve this goal?

Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet but does not specifically focus on industrial control systems. While IaaS can host applications, it lacks the specialized functionalities and security protocols necessary for managing physical processes such as gas flow.

Software-Defined Networking (SDN) is a network architecture approach that allows for more flexible and programmable network management. However, it is not directly related to the control of industrial processes and does not provide the specific functionalities needed for securing gas flow management systems.

The Internet of Things (IoT) refers to a network of interconnected devices that communicate and exchange data. While IoT devices can be involved in industrial applications, they do not encompass the comprehensive control and monitoring capabilities provided by SCADA systems, especially for legacy platforms managing critical processes.