The correct answer is C. sentinel.
A sentinel value is a special value that is used to indicate the end of a data set. It is often used in loops to control the number of times the loop iterates. For example, in a loop that reads numbers from the user, the sentinel value could be a negative number. The loop would continue to read numbers until the user enters a negative number, at which point the loop would terminate.
The other options are incorrect. Option A, “end”, is a common word that could be used to describe the end of a loop, but it is not a technical term. Option B, “finish”, is also a common word that could be used to describe the end of a loop, but it is not a technical term. Option D, “stop”, is a technical term that is used to describe a command that causes a program to stop executing. However, it is not typically used to describe the end of a loop.