The correct answer is C.
OBJ-1.6: A zero-day vulnerability refers to a hole in software unknown to the vendor and newly discovered. This security hole can become exploited by hackers before the vendor becomes aware of it and can fix it. An input validation attack is any malicious action against a computer system that involves manually entering strange information into a normal user input field that is successful due to an input validation flaw. HTTP header injection vulnerabilities occur when user input is insecurely included within server response headers. The time of check to time of use is a class of software bug caused by changes in a system between checking a condition (such as a security credential) and using the check’s results and the difference in time passed. This is an example of a race condition.