Final answer:
The actus reus of section 20 wounding is unlawful act leading to harm.
Step-by-step explanation:
The actus reus of section 20 wounding is b) Unlawful act leading to harm.
Section 20 wounding is a legal term used to describe the offense of inflicting grievous bodily harm on another person. In order to establish the actus reus (or guilty act) of section 20 wounding, it is necessary to show that an unlawful act led to the harm caused. This means that someone performed an act that is against the law and that act resulted in harm being inflicted on another person.
For example, if a person unlawfully assaults someone by using physical force against them, and as a result, the victim suffers a serious injury, this would be considered the actus reus of section 20 wounding.