Final answer:
The term "witching hour" from the given options, though traditionally associated with late-night supernatural events, can metaphorically represent the last possible moment to do something.
Step-by-step explanation:
The term used to describe the last possible moment for doing something is often colloquially referred to as the "11th hour." This expression is not directly provided as an option in the question, but it signifies a time when there is a very limited amount of time left to act. Nonetheless, the choices given are different moments or kinds of hours. The correct answer to the question, choosing from the given options, would be c) Witching hour, which is a term used to refer to a time late at night when supernatural events are thought to occur. However, please note that "witching hour" is not commonly used to denote the 'last possible moment' in a literal sense; it is a metaphorical or folklore-related term.