A boiler that provides some means of controlling the degree of superheat independently of the rate of steam generation is said to have?

A boiler that can control the degree of superheat independently of the rate of steam generation is referred to as having "controlled superheat." This means that the superheating process can be adjusted without directly depending on the amount of steam being produced at any given time. The ability to maintain an optimal superheat temperature is crucial for achieving efficient steam generation and maximizing the performance of various systems that use steam for power, heating, or other applications.

In a controlled superheat setup, adjustments can be made to achieve the desired superheat temperature based on operational needs, ensuring better steam quality and efficiency. The options that describe conditions like variable, constant, or selective superheat do not convey the same level of independent control over superheat degree relative to steam production, which is a key aspect of controlled superheat.