Final answer:
To protect its method for processing silica, Sandbox, Inc. needs a utility patent, which is the right choice for innovations in processes or improvements to technology, granting 20 years of exclusive rights to the invention. So, the correct option is c. Utility patent.
Step-by-step explanation:
To protect its intellectual property for the improved method of processing silica used in oil drilling, Sandbox, Inc. would need to secure a utility patent. A utility patent is granted for the invention or discovery of any new and useful process, product, or machine, or a significant improvement to existing technologies. This is different from a design patent, which protects the aesthetics of a product, and vastly different from a copyright, which secures original works of authorship such as books and music. Therefore, the correct option for Sandbox, Inc. is c. Utility patent.
It's essential to understand that intellectual property rights are crucial for innovation, offering an incentive for research and development by granting a temporary monopoly to inventors. Without this protection, firms like Sandbox, Inc. would face competition that might hinder their ability to recoup their investment in research and development. Patents are awarded for a specified period, typically 20 years from the date of filing, after which the invention enters the public domain.