Which of the following is considered serious physical injury to a child?

Serious physical injury to a child is characterized by injuries that result in substantial harm or long-term effects on the child’s physical health and wellbeing. The option highlighting an injury causing severe pain or impairment to functioning aligns with this definition, as it indicates a serious level of harm that can have significant repercussions for a child's health, comfort, and ability to perform everyday activities.

In contrast, the other options presented represent minor injuries that do not meet the threshold for what is typically defined as serious harm. A minor bruise that heals quickly, a scrape on the knee, and a temporary headache are all examples of injuries that would generally be considered trivial and unlikely to cause lasting damage or significantly impair a child's functioning. Therefore, the definition of serious physical injury is concerned with both the intensity of the pain experienced and the degree to which the child's normal functioning is compromised.