Answer:
The correct answer is letter "C": Is usually considered competitive.
Explanation:
Patents are grants of property given to creators on their inventions. Most patents are valid for 20 years counted from the filing date with the United States Patent and Trademark Office (USPTO). After the patent expires, other individuals can make use and exploit the creation. In such circumstances, the invention becomes competitive since it can be replicated by other entities, which was forbidden while the patent was valid.