What is meant by "manslaughter" in the Penal Code?

Manslaughter is defined in the Penal Code as an unlawful killing that occurs without malice aforethought, which distinguishes it from more severe forms of homicide such as murder. This definition encompasses situations where the killing was not premeditated or intended to cause death. Instead, manslaughter typically involves a heat of passion or extreme emotional disturbance, where the perpetrator does not have malicious intent. This is a critical aspect of manslaughter, as it recognizes the circumstances that can lead an individual to take another's life without the level of intent associated with murder.

The other answer options do not align with the legal definition of manslaughter. For example, planned killing refers to murder, which implies premeditation and malice. Killing in self-defense is justified and does not constitute unlawful killing, hence it falls outside the category of manslaughter. Lastly, while killing resulting from criminal negligence can also be an aspect of manslaughter, it is more specifically tied to the lack of intent rather than the absence of malice. Therefore, the option that most accurately captures the essence of manslaughter is the one that emphasizes the lack of malice aforethought.