Which of the following is NOT a plea that can be entered by a defendant?

The choice indicating "No contest by reason of insanity" is not a recognized plea in the legal system. In most jurisdictions, a defendant can plead guilty, not guilty, not guilty by reason of insanity, or no contest (also known as nolo contendere), but there is no established procedure for entering a plea of "no contest by reason of insanity."

The plea of "guilty" implies that the defendant admits to committing the crime, while "not guilty" asserts the defendant’s claim of innocence. "Not guilty by reason of insanity" allows a defendant to acknowledge they committed the act but claim they were not in a sound mental state at the time, which can lead to different legal outcomes. Since "no contest by reason of insanity" merges two distinct legal concepts without a valid framework in the court system, it stands out as the incorrect option among the others, which are all valid pleas defendants can enter.