What is required for software to be eligible for patenting?

For software to be eligible for patenting, it must be implemented in conjunction with a computer. This requirement stems from the U.S. patent system's need for an invention to fall within a statutory category of patentable subject matter, which includes "processes," "machines," "manufactures," and "compositions of matter." Software by itself is typically considered an abstract idea and is not patentable unless it is tied to a specific machine or device, which in many cases is a computer.

When software is developed to be run on a computer or to control a specific hardware, it adds a practical application and a technological advancement that can satisfy the requirements of patentability, such as novelty and non-obviousness. Thus, integrating software with a computer allows it to meet the eligibility criteria necessary for patent protection, showcasing a technological solution or enhancement rather than a mere abstract concept.

The need for some form of interaction with a computer or hardware is crucial in illustrating how the software functions and achieves a particular outcome, making choice C the correct one in this context. A patent claim would need to clearly delineate how the software works in relation to the hardware to demonstrate its utility and applicability in the real world.