Which of the following is NOT a common defense available under the Penal Code?

Premeditation is not a common defense available under the Penal Code because it refers to the mental state or intent of a defendant at the time of committing a crime, specifically in the context of homicide offenses. Premeditation indicates that the person thought about the crime beforehand, which is essential in determining the degree of the crime (like first-degree murder).

In contrast, the other options - insanity, self-defense, and entrapment - are recognized defenses that a defendant can use in court to argue against their culpability for a crime. Insanity refers to a mental condition that prevents a person from understanding the nature of their actions or distinguishing right from wrong. Self-defense is a justification for using force in response to an imminent threat. Entrapment involves a situation where law enforcement induces a person to commit a crime that they would not have otherwise committed. Thus, while the former three can be strategies used to defend against criminal charges, premeditation is an element of certain crimes rather than a defense.